How to be an “iPhone nature photographer”

My passion for insect macro-photography is well known, so it may come as a surprise to learn that I have, during the past year or so, also become an avid “iPhone photographer”—i.e., I actually use my iPhone for “real” photography and not just selfies or quick snapshots. This is not to say that an iPhone can do everything that a digital SLR camera can do, especially when one considers the resolution of and wealth of lens options available for the latter. Nevertheless, as the world’s best selling smart phone, the iPhone has, by way of its camera function, also become the world’s best selling camera, and even though it cannot match the power of a dSLR, there are certain situations and types of photos for which the iPhone is perfectly adapted. Having gained some level of proficiency in learning what the iPhone can and cannot do when it comes to photography, I thought I would offer this photo set of a hike I did today along the Courtois Section of the Ozark Trail as a primer for the types of photos at which iPhones excel, along with some tips and tricks I’ve learned to get the most of the iPhone’s capabilities.

An iPhone is basically a fully automated, wide-angle camera (although the user can control exposure to some extent by touching the screen at the desired point). As such, it excels at landscape and general nature photos, and its small-diameter lens also allows some use for “wide-angle macro.” iPhones do not do well in low light situations or take true macro photographs (although one can use a variety of “clip-on” lenses to achieve fairly decent macro-photographs of larger insects—I have not tried this myself). As a result, I tend to use the iPhone mostly in good light situations and break out the big camera when the lighting is more challenging or if I want to take “real” macrophotographs. As with all digital photographs, good post-processing is necessary for making iPhone photos look their best, and in general a more aggressive approach than is typical for dSLR photographs will be required. The photos that follow are intended not only to give a flavor of the day’s hike, but also demonstrate my photographic approach and provide tips on composition, exposure, and post-processing. If you have gained experience in iPhone photography and have additional tips and tricks that you would like to share, I would greatly appreciate hearing about them in the comments.

Courtois Creek - immediately at the start we had to make a decision whether we could ford the creek. It was obviously too deep in most places, and we almost turned back, but then saw a path that looked like it might be passable. With air temps of 22F, we stripped off our pants, boots, and socks, packed them in our backpacks, and waded through frigid water that reached just below our hips before reaching the other side. Rich brought a towel, so we were able to dry off before getting dressed again. The whole process took almost a full half-hour.

Courtois Creek – immediately at the start we had to make a decision whether we could ford the creek. It was obviously too deep in most places, and we almost turned back, but then saw a path that looked like it might be passable. With air temps of 22F, we stripped off our pants, boots, and socks, packed them in our backpacks, and waded through frigid water that reached just below our hips before reaching the other side. Rich brought a towel, so we were able to dry off before getting dressed again. The whole process took almost a full half-hour.

This photo was taken into the sun, which can easily result in a washed out sky. To avoid this, I minimized the amount of sky in the photo (which also allowed the ripples in the foreground to be included for a sense of motion) and then touched the screen on the sky to set the exposure. This resulted in a dark photo, but it preserved the rich colors which could then be brought out with aggressive brightening and increasing the contrast in Photoshop. A standard set of commands that I generally use for all iPhone photos (slightly increased saturation, sharpening, and de-speckling) produced the finished version.

Bluffs along Courtois Creek - massive bluffs along the other side of the creek sported fallend boulders the size of dump trucks.

Bluffs along Courtois Creek – massive bluffs along the other side of the creek sported fallen boulders the size of dump trucks.

Another photo taken in the direction of the sun, causing the shadowed side of the rock to turn out very dark. Again I touched the screen on the sky to preserve the blue color and then aggressively lightened in Photoshop. Aggressive brightening generally requires a more aggressive increase in contrast, followed by the standard command set mentioned for the first photo.

We were feeling good about our decision to ford the creek as we hiked below spectacular bluffs.

We were feeling good about our decision to ford the creek as we hiked below spectacular bluffs.

This photo required fairly minimal post-processing since it was shot away from the sun and, thus, had decent native exposure. The bluff face was a little dark and needed minor brightening, but as always I set the exposure in the brightest area of the photo and then post-corrected the dark areas (this is much easier than the opposite, i.e., darkening areas that are too bright, as such areas are often blown and cannot be fixed).

Ozark Trail blaze.

Ozark Trail blaze.

A very close-up shot of a trail blaze. The main watch out with such photos is to ensure the plane of the camera matches the subject precisely, otherwise distortion will cause elongation of one side (making the blaze a trapezoid rather than a rectangle). In post-processing I set the white point in levels by greatly magnifying the image and clicking on a very white part of the blaze to get a more natural looking white rather than the dirty gray that often results when shooting largely white subjects.

Blufftop view of Courtois Creek - from a vantage point several hundred feet above the creek we could look down on our crossing point. I have a fear of heights but nevertheless hung onto the treefall in front of me to inch out for a clear view.

Blufftop view of Courtois Creek – from a vantage point several hundred feet above the creek we could look down on our crossing point. I have a fear of heights but nevertheless hung onto the tree fall in front of me to inch out for a clear view.

This was another photo taken fairly towards the sun. I wanted just a thin band of sky to add a sense of scale to the downward-looking view, but with little sky the camera automatically wanted to expose for the darker foreground, thus blowing the sky. To prevent this, I tilted the camera up slightly to get more sky, touched the screen on the sky to set exposure, then tilted back down to the composition I wanted and took the shot. Post-processing involved aggressive brightening as described for the first two photos above.

Sapsucker damage on an old tree.

Sapsucker damage on an old tree.

I approached this tree from an angle facing the sun, so I simply waited until we passed it and could turn to place the sun behind me while shooting this tree. The trick is to get the right distance for a composition that doesn’t include too much wasted space at the foot of the tree or in its canopy, so this requires some walking back and forth until the right composition is achieved (I do not use the zoom function on the camera unless I have to because of the loss of resolution).

Close-up view of sapsucker damage. Obviously they have been using this tree for many years

Close-up view of sapsucker damage. Obviously they have been using this tree for many years

A closer view of the sapsucker damage—again this is mostly a compositional challenge, which I met by getting close enough to have this interesting “looking up” perspective but still far enough away to include the lowest ring of damage at the bottom of the photo and the highest at the top. Little post-processing other than the standard set was required for this sun-behind-me photograph.

Crystallifolia forms when water drawn from the soil by certain plants oozes out of the stem and contacts frigid air. Additional water pushes out the ice, then freezes itself, resulting in long, thin ribbons of ice that curl around themselves

Crystallofolia forms when water drawn from the soil by certain plants oozes out of the stem and contacts frigid air. Additional water pushes out the ice, then freezes itself, resulting in long, thin ribbons of ice that curl around themselves

For photographing crystallofolia and other small, ground-dwelling features, I like to turn the iPhone so that the lens is on the bottom edge to achieve a true ground-level perspective. The macro capabilities of the iPhone are limited, so in this case I used the zoom function (maybe about 1/3 to full zoom), centered the feature in the photo to get the best exposure and focus, and then did a little more cropping post-processing at the bottom of the photo to minimize the amount of blurred foreground. Again, a mostly white subject such as this tends to come out dull in the native photograph, so I enlarged the image greatly in Photoshop, opened Levels, clicked on set white point, and then clicked on the whitest portion of the subject that I could find to achieve a more ‘naturally’ white subject. It can take a few tries to find a spot in the image that doesn’t result in unnatural over-whitening of the subject—one must play around a bit to find it.

Crustose lichens abound on the dolomite bedrock exposures along the "Narrows" - a long, narrow ridge between the Courtois and Huzzah Creek Valleys.

Crustose lichens abound on the dolomite bedrock exposures along the “Narrows” – a long, narrow ridge between the Courtois and Huzzah Creek Valleys.

Again, I like to use a low perspective for ground features such as these lichen-encrusted rocks strewn across the forest floor. If you let the iPhone focus naturally, it tends to focus on subjects closer to the middle of the photo, so be sure to touch the screen on the foremost subject to set the focus in the foreground. Photos with contrasting colors such as the greens, browns, and blues in this one generally benefit from a little more aggressive increase in saturation (maybe 15-20%) than I normally use for iPhone photos (usually 5-10%).

Close-up view of crustose lichens.

Close-up view of crustose lichens.

A semi- wide-angle macro photograph that combines a lichen encrusted rock in the foreground with forest and sky in the background. The camera will automatically focus on the background, so touch the screen at the top of the foreground object to set focus. It also helps to pan back a little bit to include more in the frame than is desired, then crop a little in Photoshop as the lower part of the foreground object will tend to be out of focus unless it is a perfectly vertical surface (rare). In this photo I cropped out about 1/5 from the bottom and a corresponding amount on each side to maintain original aspect ratio.

More dolomite exposures with crustose lichens.

More dolomite exposures with crustose lichens.

Highly dimensional foreground objects add depth and perspective to low-angle shots. Again, it is better to get a little more in the photo than desired and the crop slightly afterwards than to get too close and not be able to do anything about it. Taking the native shot a little further back also ensures that the entire foreground object is in focus.

Fruticose lichens and moss intermingle in particularly moist spots.

Fruticose lichens and moss intermingle in particularly moist spots.

Like the close-up photo of the lichen-encrusted rock above, this photo of intermingled moss and fruticose lichens benefits from a low perspective with a high color contrast immediate background (fallen leaves) and blurred deep background (forest/sky) to add perspective. While the latter is not completely blurred, but it’s enough that it doesn’t detract from the main subject. The latter has maximal focus by backing up slightly for the shot and then cropping off the bottom out-of-focus portion in Photoshop. Again, I increased saturation a little more than usual to emphasize the value contrast.

Friend and Ozark Trail co-conspirator Rich Thoma looks out over the Huzzah Creek Valley.

Friend and Ozark Trail co-conspirator Rich Thoma looks out over the Huzzah Creek Valley.

The main challenge with this photo was the shadow cast over Rich by the trees behind him. Setting the exposure on him resulted in a washed out sky, which I really wanted to preserve because of the textured clouds. I also wanted to include a good portion of the sky to give the sense of looking out over a far-below valley, so I set the exposure for the sky. The resulting photo had a good sky, but Rich was hidden in a darkly shadowed area. I used lighten shadows in Photoshop to brighten Rich and the shadowed area where he is standing, and I used aggressively increased saturation to make the many different shades of brown in the rest of the photo pop out.

An ancient red-cedar snag hugs the bluff tops overlooking the Huzzah Creek Valley.

An ancient red-cedar snag hugs the bluff tops overlooking the Huzzah Creek Valley.

This photo had largely the same challenges and was dealt with in the same manner as the previous. The ancient red-cedar snag is an interesting and unusual subject, and I first tried a portrait orientation, but I decided I liked this landscape orientation better because of the ability to include living red-cedar to add a sense of time contrast.

Icicles form on an undercut below the bluff top.

Icicles form on an undercut below the bluff top.

Whenever I find icicles hanging from a rock overhang, I like to provide a more unusual perspective by getting behind the icicles and looking out onto the landscape. It can be hard to get the camera to focus on the icicles rather than the distant landscape—just keep touching them on the screen until it works. I used shadow lightening in Photoshop to brighten the dark rock surfaces in the foreground.

A cap of resistant dolomite lines the top of the Huzzah Creek Valley.

A cap of resistant dolomite lines the top of the Huzzah Creek Valley.

This was a difficult photograph—sun on the pines/cedars on the left overexposed them, while shadows on the naturally dark rock bluff surfaces left them underexposed. This photo was made fairly acceptable by using both “darken highlights” and “lighten shadows” (careful—too aggressive with these features results in unnatural-looking photos), followed by brightening and increasing the contrast, and finally by increasing the saturation. It’s still not a great photo, but sometimes you get what you get.

More icicles.

More icicles.

This larger set of icicles was nicely positioned in front of an interestingly sloped landscape with the sun coming from the left. Again, I got behind them, kept touching the screen on the icicles until the iPhone focused on them, and then adjusted the white point setting in Levels in Photoshop to really make them pop against the rich browns of the landscape behind.

Icicles were especially abundant in this section of the bluff tops.

Icicles were especially abundant in this section of the bluff tops.

A fairly easy shot due to the direction of the sun that required no more than the usual amount of post-processing. Note the perspective, which was to have the rock feature begin right at the bottom left corner of the photograph with some sky above it.

Despite subfreezing air temperatures, sunlight causes water to drip from overhanging icicles, causing ice stalagmites on the ground beneath.

Despite subfreezing air temperatures, sunlight causes water to drip from overhanging icicles, causing ice stalagmites on the ground beneath.

This photo had some dark areas in the foreground that were cropped out, and to emphasize the ice I was more aggressive post-processing with brightening and increasing the contrast. Again, as with most photos with a lot of white in the subject, I adjusted the white point in Photoshop Levels to reduce the “dinginess” that seems natural for ambient light iPhone photos.

Icicles glisten in the frigid sunlight.

Icicles glisten in the frigid sunlight.

In this case, the sun glistening on the icicles and a deep recess behind them provided a natural contrast that I further emphasized in post-processing, along with brightening and setting white point. The icicles suffer from distortion due to my low angle (I’m not that tall!), which I tried to fix with Photoshop’s distort feature but wasn’t satisfied with the result.

Close-up of ice stalagmites, revealing the twigs and petioles around which they have formed.

Close-up of ice stalagmites, revealing the twigs and petioles around which they have formed.

The approach with this photo was very much like that used for the close-ups of the lichen-encrusted rocks and intermingled lichens/moss photos—i.e., I backed up a bit to include more foreground than I wanted (which will be blurred at the bottom after setting the focus point on one of the stalagmites) and then cropped it out in post-processing. White subject = setting white point and using more aggressive brightening and contrast.

 Ted MacRae Yesterday ·  Rock, ice, and sunlight converge along the bluff tops


Rock, ice, and sunlight converge along the bluff tops

Again, the formation starts at the lower corner, and in this case the foreground (the right side) also contains an interesting clump of icicles. With the sun behind me, little was required to assure proper exposure, and only normal post-processing was required.

Moss with fruiting structures on a fallen log.

Moss with fruiting structures on a fallen log.

This moss on a fallen log was actually one of the more difficult photographs I took. I took the photo at an angle so that the background fruiting structures would form a solid, blurred red horizon to add depth, but in doing this the iPhone didn’t know where I wanted to focus and kept choosing the background. To force it to “choose” the foreground fruiting structures, I tilted the camera down so that only the foreground was in the frame, touched the screen on the fruiting structures in the back part of the screen to set focus where I wanted, then tilted the screen back again to include the background fruiting structures distant blurred background for perspective. One must shoot quickly when doing this or the iPhone will automatically readjust its focus to the background. I’ve tried shots such as this with the sky in the background, but in my experience the iPhone cannot focus on very thin foreground objects with the sky in the background, and the difference in brightness between the background and foreground is especially difficult to correct. Like the other semi- wide-angle macro shots above, I used the zoom feature (slightly), included a little more in the photo than I wanted, and then cropped out the overly blurred bottom portion of the photo.

Mushrooms on a fallen log.

Mushrooms on a fallen log.

Here is a typical photograph that someone might take of these large, saucer-sized mushrooms on a fallen log. In addition to being a pedestrian view of such a subject, it seems that iPhones sometimes have difficulty registering the correct color for photos taken straight down to the ground. This photo required quite a bit of color correction, and I’m still not overly satisfied with the result.

"Bug's eye" view of mushrooms on a fallen log.

“Bug’s eye” view of mushrooms on a fallen log.

As an alternative, I suggest getting low to photograph subjects such as this. The iPhone, with its lens against one edge and screen view, is well-adapted to take such low-angle photos, resulting in a much more interesting photo than the typical “looking down” perspective exemplified above. Inclusion of a little bit of sky in the background also provided some nice color contrast, made easier by shooting away from the sun, which was further emphasized in post-processing by increasing the saturation. As with the other semi- wide-angle macro photographs, a little bit of cropping along the bottom (but do keep the original aspect ratio) also benefited the photograph.

Moss covering the rock exposures in a delightful valley leading up from the Huzzah Creek Valley indicate an abundance of moisture.

Moss covering the rock exposures in a delightful valley leading up from the Huzzah Creek Valley indicate an abundance of moisture.

Last, but not least, this photograph of shaded, heavily moss-laden rock outcroppings bordering a small waterfall needed to be shot very dark in order to avoid “blowing” the sky in the background. Simply pointing and shooting into the shade will cause the iPhone to correctly expose the rocks, but the sky will be blown rather than retaining its blue color. Like the first two photos, I composed the image, then touched the screen on the sky to reduce the exposure. Again, this resulted in a photo that was very dark in the foreground, but this was easily corrected by aggressive brightening, adding contrast, and increasing the saturation post-processing to achieve a nice mix of browns and greens while preserving the blue sky background. In forest shots such as this with a lot of vertical objects, pay attention to distortion while composing the photo to avoid having trees at the edge of the photo “bowing” inwards at their tops. Sometimes this can be avoided by minor adjustments to the tilt of the iPhone while taking the shot, but if your position in the landscape is such that camera tilt alone is not enough to prevent this without losing the desired composition then go ahead and shoot the desired composition and use the “distortion” tool in Photoshop to correct the distortion this works best if bowing is minor).

I hope you have enjoyed this iPhone nature photography tutorial. If you have additional ideas or suggestions please let me know, and also I would be glad to hear of any related subjects you would like me to cover.

Copyright © Ted C. MacRae 2013

The wondrously and eerily beautiful Mono Lake

During my recent Great Basin collecting trip, we stopped briefly at one of my favorite places in the world—Mono Lake in eastern California. My last visit was almost 20 years ago, so it was a thrill for me to see the strange tufa moonscape once again after so many years.

Mono Lake

Mono Lake has no eventual outlet to the ocean. As a result dissolved salts in runoff from the surrounding landscape have accumulated in the lake, resulting in water with high pH levels.

Mono Lake

The late day shadows created a black/white tufa landscape.

Mono Lake

Conservation actions have raised lake levels from their historical lows resulting from diversion of water to Los Angeles, but they have still not recovered to their former levels.

Mono Lake

I held the camera barely above the water’s surface to get this shot. It took several tries to get just a thin sliver of perfectly horizontal water. Yes, it would have been easier to hold the camera higher, look through the viewfinder and then crop, but I wanted the widest view possible (besides, doing that would seem like “cheating”).

Mono Lake

Tufa forms when calcium from underwater springs comes into contact with carbonates in the lake water, causing a chemical reaction that produces calcium carbonate (limestone). The calcium carbonate settles around the underwater spring and over time builds a tufa tower. This happens only underwater, and the tufa towers seen here are visible only because of the lowered lake level resulting from water diversion. Unless the lake level is restored completely, these towers are “dead” and will eventually erode away.

Mono Lake

Smoke and haze from the Rim Fire burning near Yosemite boils over the eastern slope of the Sierra Nevada.

Mono Lake

Mono Lake supports the second largest nesting population of California gulls after Utah’s Great Salt Lake.

Mono Lake

The water level at Mono Lake has dropped not only in recent years because of humans, but over several thousand years. At the end of the last ice age the water level was hundreds of feet higher than today and the lake 5 times its present size.

Mono Lake

Late day shadows, wildfire haze, and perfectly still waters create a surreal scene.

Copyright © Ted C. MacRae 2013

Red Rock Canyon National Conservation Area

Calico Hills.

Calico Hills at Red Rock Canyon National Conservation Area | Las Vegas, Nevada.

In mid-August I traveled to Las Vegas with several hundred of my colleagues for week-long, organization-wide meetings. As would be expected, the itinerary was full with little time for diversions, but management was kind enough to call time out on Wednesday afternoon and offer up a choice of activities for us to choose from. Golf, a tour of Hoover Dam, and a massage at the spa were popular choices, but for me and a few other more adventurous sorts the natural choice was a jeep tour of Red Rock Canyon National Conservation Area. I’ll be honest—I hadn’t heard of RRCNCA before then (but then I’d never been nor even had the desire to visit Las Vegas, either), and I’m also not really a guided-tour-sort-of-guy. All I knew was that I was going to have a chance to get outside, at least for short stints, in rugged, natural terrain (something I need a regular dose of in normal circumstances, much less when I’m in the midst of week-long meetings). What I found, however, was an incredible landscape of rock, sky, color and texture that ranks among the most interesting landscapes I’ve ever seen. While I questioned it at the time, I’m really glad I brought my big camera. Not only did the landscape shots turn out so much better than they would have had I decided to settle for iPhone shots, but my long lens (100mm macro) proved to be essential for shots of some petroglyphs that visitors are kept a good distance from. I’ll not go too much into the geology of RRCNCA, as such information can easily be gleaned from Wikipedia (or for more detailed information see this excellent PDF by Tom Battista).

Some of my favorite photos from the afternoon are shown in the following slide show. The photos here are notably free of people (with two very slight exceptions)—more people-based photos featuring the colleagues I was with can be found in my “Red Rock Canyon – Aug 2013” album at my Facebook page.

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Copyright © Ted C. MacRae 2013

Oklahoma Collecting Trip iReport

I’m back home after my week-long collecting trip to western Oklahoma, and at the risk of sounding hyperbolous I can only describe it as one of the most successful collecting trips I’ve ever had. Seriously! These kinds of trips don’t happen all that often for a variety of reasons—timing is off, rains didn’t happen, weather was uncooperative, etc. etc. Once in a while, though, everything comes together, and this was one of those times. The trip was also a return to my roots so to speak—I’ve been rather distracted in recent years with tiger beetles, but jewel beetles (family Buprestidae) and, to a lesser extent longhorned beetles (family Cerambycidae), are really the primary focus of my taxonomic studies. It had been several years since I’d had a good “jewel beetle trip,” so that was the focus of this trip. In planning the trip, I recalled seeing jewel beetle workings in several woody plant species in the same area during last September’s trip, and the occurrence of May rains seemed to bode well for my early June timing.

Gloss Mountains State Park, Major Co., Oklahoma

Gloss Mountains State Park, Major Co., Oklahoma

My instincts proved to be justified—in seven days in the field I collected an estimated 1000–1500 specimens representing at least two dozen species of Buprestidae and a dozen or more Cerambycidae. More important than the numbers, I collected a number of species in good series that I have either not or only rarely collected before, and in fact the second beetle that I collected turned out to be a new state record! Of course, I also brought along my full-sized camera and associated gear and photographed many of the species that I collected. I will feature these photos in future posts, but for this post I thought it might be fun to give a high level view of the trip illustrated only with photos taken with my iPhone (which I also carry religiously in the field with me). The iPhone is great for quick snaps of scenery and miscellaneous plants and animals for which I don’t feel like breaking out the big camera, or as a prelude to the big camera for something I’d like to share right away on Facebook. Moreover, there are some types of photos (landscapes and wide-angles) that iPhones actually do quite well (as long as there is sufficient light!).

Gloss Mountains State Park, Major Co., Oklahoma

Atop the main mesa at Gloss Mountains State Park, Major Co., Oklahoma

My first destination was Gloss Mountains State Park (Major Co.), a stunning system of gypsum-capped, red-clay mesas. I’ve already found a number of rare tiger beetles here such as Cylindera celeripes (Swift Tiger Beetle), Amblycheila cylindriformis (Great Plains Giant Tiger Beetle) and Dromochorus pruinina (Frosted Dromo Tiger Beetle), and in the past two falls I’ve found two interesting jewel beetle records: Chrysobothris octocola as a new state record, and Acmaeodera macra as a northern range extension. On this trip, I started out beating the mesquite  (Prosopis glandulosa) and immediately got the longhorned beetle Plionoma suturalis—a new state record! They were super abundant on the mesquite, and I collected several dozen specimens along with numerous C. octocola as well. I then moved over to the red-cedar (Juniperus virginiana), which was showing a high incidence of branch dieback, and collected nice series of several buprestids, including what I believe to be Chrysobothis ignicollis and C. texanus. Up on top of the mesa there are small stands of hackberry (Celtis laevigata) and soapberry (Sapindus saponaria), both of which are very good hosts for Buprestidae. Not much was on the soapberry, but I beat large series of several Buprestidae from the hackberry, including what I believe to be Chrysobothris caddo and—the real prize—Paratyndaris prosopis! My old friend C. celeripes was also out in abundance, so I collected a series to add to my previous vouchers from this site. Back down below, I marveled at a juvenile western diamondback rattlesnake (Crotalus atrox) in the area where I found some more A. cylindriformis larval burrows. Daylight ran out before I could dig them up, and after 11 hours in the field I was exhausted, so I returned the next morning and got one 1st- and two 3rd-instar larvae and went back up on top of the mesa and beat several more P. prosopis from the hackberry.

Bullsnake (Pituophis catenifer sayi) | Alabaster Cavern State Park, Woodward Co., Oklahoma

Bullsnake (Pituophis catenifer sayi) | Alabaster Cavern State Park, Woodward Co., Oklahoma

My second stop was at Alabaster Cavern State Park (Woodward Co.), where C. celeripes was again abundant on the gypsum-clay exposures surrounding an impressive gorge thought to be a collapsed cave complex. I focused on beating hackberry because of the success with buprestids on this plant at Gloss Mountains SP, and although they were not quite as abundant here as at Gloss Mountains I still managed to end up with good series of C. caddo and several species of Agrilus. Because I had spent the morning at Gloss Mountains, I had only a partial day to explore Alabaster Caverns and, still getting used to the weight of the camera bag on my back, decided to leave the big camera in the car. This was a mistake, as I encountered my first ever bullsnake (Pituophis catenifer sayi) and had to settle for iPhone photos of this species—the photo above being the best of the bunch. An approaching storm put an end to my second day after another 10 hours in the field, and I drove an hour to Woodward.

Moneilema sp. on Opuntia phaecantha | Alabaster Cavern State Park, Woodward Co., Oklahoma

Moneilema sp. on Opuntia phaecantha | Alabaster Cavern State Park, Woodward Co., Oklahoma

My third day started out at nearby Boiling Springs State Park, a riparian oasis on sandy alluvium alongside the nearby Cimarron River. The woodlands are dominated by hackberry and American elm, and although a few buprestids were beaten from hackberry and honey locust (Gleditisia triacanthos), the numbers and diversity were not enough to hold my interest in the spot. After lunch, I decided to return to Alabaster Caverns SP and explore some other areas I had not had a chance to explore during the previous partial day. It’s a good thing that I did, as I ended up finding a nice population of longhorned cactus beetles in the genus Moneilema associated with prickly pear cactus (Opuntia phaecantha). I collected a nice series of adults and also learned a few lessons in how to photograph these beetles on their viciously protective host plants. The photo above gives a taste of what will come in the photos that I took with the big camera. After eight hours in the field and darkness falling, I drove two hours to Forgan in Beaver Co.

Beaver Dunes State Park, Beaver Co., Oklahoma

Beaver Dunes State Park, Beaver Co., Oklahoma

Day 4 in the field started out cold and ominous, having stormed heavily during the previous night and with thick clouds still hanging in the sky. I feared the day might be a wash but decided to venture to Beaver Dunes State Park anyway and take my chances (beating can still be productive even in cold weather as long as the foliage is not wet). It’s a good thing that I did, as the buprestids were as numerous as I’ve ever seen them. The park’s central feature is a system of barren sand dunes that are frequented by ORV enthusiasts and surrounded by hackberry woodlands. The park also has a reservoir and campground, around which are growing a number of cottonwoods (Populus deltoides).

Hackberry Bend Campground, Beaver Dunes State Park, Beaver Co., Oklahoma

Hackberry Bend Campground, Beaver Dunes State Park, Beaver Co., Oklahoma

These hackberrys and cottonwoods proved to be extraordinarily productive. On the former I collected large series of several species of Chrysobothris and Agrilus, and while I collected fewer Buprestidae on the latter, these included Agrilus quadriguttatus and Poecilonota cyanipes! The latter species I had never collected until last year (from Cerceris fumipennis wasps), and beating the lower branches of the declining cottonwoods produced a series of about a dozen specimens. I also got one specimen on black willow (Salix nigra), along with a few Chrysobothris sp. and what I take to be Agrilus politus. Also in a low branch of one of the cottonwoods was a bird’s nest with a single egg that, according to Facebook comments, either represents the American Robin or a Gray Catbird. (I returned the next day and saw two eggs in the same nest.)

American Robin or Gray Catbird nest w/ egg | Beaver Dunes State Park, Beaver Co., Oklahoma

American Robin or Gray Catbird nest w/ egg | Beaver Dunes State Park, Beaver Co., Oklahoma

As the day drew to a close, I found two interesting longhorned beetle species at the edge of the dunes: one large, powdery gray Tetraopes sp. on milkweed (Asclepias sp.), and huge numbers of Batyle ignicollis evidently perched on the yellow spiked inflorescence of an as yet undetermined plant. I have seen this species on many occasions, but always in low numbers, yet here were literally hundreds of individuals on the plants, all having assumed a characteristic pose on the inflorescence suggesting that they had bedded down for the night. I only spent eight hours in the field on this day because of the late start, and as darkness approached I began the two-hour drive to Boise City.

Black Mesa landscape

Sculpted sandstone landscape in the vicinity of Black Mesa State Park, Cimarron Co., Oklahoma

The final two days in the field were supposed to be spent exploring the area around Black Mesa in the extreme northwest corner of Oklahoma, and another hour of driving was needed to get to the area from Boise City. I first went to Black Mesa State Park, and while the landscape was stunning (see above) the area was extremely dry. I feared the collecting would not be at all productive in this area but wanted to give the area a good effort before making a call. As I approached the entrance to the park, I saw a jeep parked by the side of the road with a license plate that read “Schinia,” which I recognized as a genus of noctuid moths that are very popular with collectors. I pulled over and talked to the driver, who was indeed a lepidopterist from Denver and had just arrived himself. We talked and exchanged contact information, and learning of my interest in beetles he directed me to a small stand of Gambel oak (Quercus gambelii) and one-seed juniper (Juniperus monosperma) on a sculpted sandstone escarpment not far from the park. I found the spot, and although I beat three Chrysobothris sp. from the first juniper tree that I whacked, another hour of beating produced only one more beetle from the juniper and nothing from the oak. I returned to the spot where we had met and encountered him again on his way out! We stopped and chatted again and found a few specimens of what I take to be Typocerus confluens on the yellow asters, but by then I was having my doubts about staying in the area. I told him I was going to check out a ravine in the park and then decide.

Petrified forest | Black Mesa State Park, Cimarron Co., Oklahoma

Petrified forest | Black Mesa State Park, Cimarron Co., Oklahoma

The petrified forest ended up being the only interesting thing I found in the ravine—the area was so dry that I think even the real trees were almost petrified! At any rate, it was clear that I was not going to have much success in this area. I looked at my watch, knowing that it would take three hours to drive back to Beaver Dunes, and estimated that if I left now I could get in about three hours of collecting at Beaver Dunes where I’d had so much success the previous day. Thus, I did what I rarely do on a collecting trip—drive during the afternoon!

Beaver Dune

The main dune at Beaver Dunes State Park, Beaver Co., Oklahoma.

A chunky grasshopper nymph inhabiting the dune

A chunky grasshopper nymph inhabiting the main dune.

I arrived back at Beaver Dunes with several hours of daylight still remaining, so I decided to take a look around the main dunes before heading towards the woody plants. I’ve actually visited Beaver Dunes previously, on the tail end of a fall tiger beetle trip in 2011. At that time I had seen only the rather common and widespread species Cicindela formosa (Big Sand Tiger Beetle) and C. scutellaris (Festive Tiger Beetle), but I thought there could still be a chance to see the much less common C. lengi (Blowout Tiger Beetle). Early June, however, is a little late to see the spring tigers, and in fact I saw only a single C. formosa. Nevertheless, I find dune habitats irresistible—alien habitats occupied by strange plants and animals, and I spent a bit of time exploring the main dune before heading back towards where I had collected so many Buprestidae the previous day.

Low water levels in the reservoir at Beaver Dunes are a result of three years of drought.

Low water levels in the reservoir at Beaver Dunes are a result of three years of drought.

Western Oklahoma, like many parts of the central U.S., has suffered rather severe drought conditions for the past several years. This was evident not only in the large amount of branch dieback seen in the woody vegetation of the area (and probably a contributor to my success at collecting Buprestidae) but also the very low water level in the park reservoir. In the photo above the small cottonwood saplings in the foreground and large cottonwood trees in the left background indicate the normal water level. Cottonwoods, of course, like to keep their feet wet, and the trees around this reservoir—left high and dry by the drought—have responded with major branch dieback and lots of subsequent adventitious sprouting at the bases of the main branches. It was from this adventitious growth that I had beaten most of the Poecilonota cyanipes that I collected the previous day, so I repeated the cottonwood circuit in the hopes of collecting more. Not only did I collect more, but I collected twice as many as the previous day, so I ended up with a very nice series of more than two dozen individuals of the species from the two days collecting. I also did a little more beating of the hackberry trees which had produced well the previous day and collected several more Chrysobothris caddoC. purpureovittata, and Agrilus spp. such as A. leconteiA. paracelti, and perhaps others. When I arrived I was unsure whether I would stay here the following day, but eventually I decided I had sampled the area about as well as I could and that I would go back to the Gloss Mountains for my last day in Oklahoma. Thus, as the day began to wane I began hiking back to the car and spent the next two hours driving back to Woodward to spend the night.

Steep slope below the main mesa | Gloss Mountains State Park, Major Co., Oklahoma

Steep slope below the main mesa | Gloss Mountains State Park, Major Co., Oklahoma

Echinocereus sp. | Gloss Mountains State Park, Major Co., Oklahoma

Echinocereus sp. | Gloss Mountains State Park, Major Co., Oklahoma

Arriving at the Gloss Mountains the next morning was like coming home! I’ve spent so much time at this place and found so many great insects, yet every time I come here I find something new. Today, however, my goals were more modest—I wanted to improve on my series of Paratyndaris prosopis and Chrysobothris texanus, so I focused most of my time beating the hackberry and juniper on top of the mesa and continued beating the juniper down below as well. Success! I collected four more Paratyndaris off of the hackberry, but the C. texanus were far more abundant on this day than they were earlier in the week—I probably got another two dozen individuals of this species. Of course, I also got distracted taking photographs of a number of things, so the day went far more quickly than I realized. I wanted to leave around 6 pm and get in about three hours of driving so that I would have time to make it into Missouri the next morning and have a nice chunk of time to collect before finishing the drive and arriving home on Saturday night. It was actually closer to 7:30 pm before I hit the road, the reason for the delay being the subject of a future post (I will say that BioQuip’s extendable net handle comes in handy for much more than collecting tiger beetles!).

Dolomite glades | Hercules Glades Wilderness, Taney Co., Missouri

Dolomite glades | Hercules Glades Wilderness, Taney Co., Missouri

Long Creek | Hercules Glades Wilderness, Taney Co., Missouri

Long Creek | Hercules Glades Wilderness, Taney Co., Missouri

For my last day of collecting, I decided to stop by at one of my favorite spots in the White River Hills of extreme southwestern Missouri—Hercules Glades Wilderness in the Mark Twain National Forest. I’ve been to this place a number of times over the years, but in recent years my visits have usually been late in the season to look for the always thrilling to see Cicindelidia obsoleta vulturina (Prairie Tiger Beetle). It had actually been about 25 years since I’d visited these glades during the spring, and because of the success I’d had collecting in Oklahoma I was really optimistic that I would find the same here. Sadly (and inexplicably), insect activity was very low, and it didn’t take long for this to become apparent as branch after branch that I beat along the trail through the dry-mesic forest down to Long Creek yielded nothing. By the time I got to the creek I still had not collected a single beetle. A consolation prize was found along the creek, as beating the ninebark (Physocarpos opulifolius) produced a few specimens of the pretty little Dicerca pugionata, and a couple more consolation prizes were found further up the trail approaching the main glade when I saw a Cylindera unipunctata (One-spotted Tiger Beetle) run across the trail and then beat a single Agrilus fuscipennis from a small persimmon (Diospyros virginiana) tree at the edge of the glades. It had been about 25 years since I last collected the latter species, so I was very happy to see it, but no more were seen despite beating every persimmon tree that I saw during the rest of the day. At the end of the day, I had hiked seven miles and collected only six beetles—a rather inauspicious ending to what was otherwise a wonderfully successful trip.

A rare ''selfie''

The author takes a rare ”selfie” at Gloss Mountains State Park.

Arriving back at the car at the end of the day on the last day of an extended collecting trip is always a little depressing—despite the vagaries of travel, cheap hotel beds, meals on the go, and general exhaustion, I’m never happier than I am when I am in the field. Still, the success that I’d had during this trip did much to ease my depression, and arriving home late that night and seeing my girls again (who waited up for me!) finished off any remaining depression.

© Ted C. MacRae 2013

Taum Sauk Mountain – Missouri’s High Point

Although spring is now well underway in the middlin’ latitudes of Missouri, it was only a few short weeks ago that winter was still with us.  For my last winter hike of the season, I returned to perhaps my favorite stretch of my favorite trail in all of Missouri – the Mina Sauk portion of the Taum Sauk Trail on Taum Sauk Mountain.  Located in the rugged St. Francois Mountains (the “epicenter” of the Ozark Highlands), Taum Sauk Mountain is Missouri’s highest peak.  I say “peak” with a bit of reservation – at 1,772 feet it hardly compares with the high peaks of the Rocky Mountains or even the much mellower Appalachians (and certainly not with those of my beloved Sierra Nevada).  Nevertheless, unlike the remainder of the Ozark Highlands, the St. Francois Mountains are true mountains initially formed through a series of volcanic events occurring well over a billion years ago.  They, and the rest of the Ozark Highlands, have been shaped to their current form by repeated cycles of uplift and subsequent erosion.  

During their Precambrian prime, the St. Francois Mountains reached heights of 15,000 feet (the “ancient” Appalachians, in the meantime, were still just a twinkle in Mother Earth’s eye).  Rain and wind and the vastness of time have reduced them to nubs, leaving only the most ancient of volcanic rocks as testament to their former glory.  Although most of what is now the Ozark Highlands was inundated repeatedly later in the Palaeozoic (laying down the sediments that were then uplifted and “carved” to their current shape), the highest peaks of the St. Francois Mountains may be among the few areas in the United States never to have been completely submerged under those ancient seas.  Standing atop Taum Sauk Mountain, it is tempting to visualize today’s craggy terrain as a fossil of that ancient landscape – the peaks representing the former islands of rhyolite, their slopes barren and lifeless in stark contrast with the exploding diversity of bizarre life forms appearing in the tropical waters that surrounded them.

The sterile, volcanic rocks of the St. Francois Mountains support an abundance of open, rocky glades – especially on their peaks and southern and western slopes – that are home to a number of plants and animals more typically found in the tallgrass prairies further west.  Indian grass (Sorghastrum nutans) and little bluestem (Schizachyrium scoparium) thrive in clumps between the large, pink boulders that are strewn across the landscape and which provide shelter and sunning spots for animals ranging from the charismatic eastern collared lizard (Crotaphytus collaris) to the smaller but no less beautiful splendid tiger beetle (Cicindela splendida).  The surrounding forest is historically an open woodland with a rich, herbaceous understory and widely-spaced, drought-tolerant trees such as shagbark hickory (Carya ovata), post oak (Quercus stellata), and blackjack oak (Quercus marilandica).  These woodlands and glades are a fire-mediated landscape dependent upon periodic burns to maintain their vegetative character.

A trail begins at “High Point”, marking the summit of Taum Sauk Mountain and the highest point in Missouri.  A granite slab next to the summit rock documents the elevation at 1,772.68 feet MSL (Mean Sea Level).  The Mina Sauk Falls Trail, a rugged three-mile loop that joins the Taum Sauk Section of the Ozark Trail, leads to the tallest wet-weather waterfall in Missouri, Mina Sauk Falls.  During periods of high water flow, water gushes over the edge and drops 132 feet over a series of rocky ledges.  Water was flowing lightly during my late winter visit; nevertheless, looking out from above the falls (see photo above) offers one of the most spectacular vistas available in Missouri.  A rather difficult hike down the side of the mountain to the bottom of the falls is also well worth the effort, although clear views of the entire falls are difficult to find in the dense, moist forest below (it was here that I photographed the spectacular Ozark Witch Hazel).

A second unique geological feature lies about a mile farther down the Ozark Trail – Devil’s Toll Gate.  The rocks stand 30 feet high on either side of this eight-foot-wide, 50-foot-long fissure.  The gap probably began as a vertical fracture in the rock that has been enlarged by subsequent weathering. Over time the fissure will continue to widen, as the rocks on either side lose height.

Returning to High Point at the end of the hike, I noticed that the summit was a little higher than when I started my hike – whether this was through additional uplift of the underlying mountain or a depositional event I cannot say.  Nevertheless, I estimated Missouri’s new highest elevation to be approximately 1,773.01 feet MSL!

Copyright © Ted C. MacRae 2010

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Up the Glacial Staircase

During last year’s visit to Lake Tahoe, we attempted to hike Eagle Falls Trail, one of Lake Tahoe’s most scenic and popular trails.  Beginning at the Hwy 89 trailhead above Emerald Bay, this trail climbs a dramatic ‘glacial staircase’ with steep, narrow gorges connecting a series of deep lakes and meadows.  Each of these lakes, and indeed Emerald Bay itself, was formed as a result of glaciers that carved Lake Tahoe’s granite shores until as recently as 10,000 years ago – leaving behind scars of incomparable beauty.  Eagle Lake perches atop one of these steps – only a short, one-mile hike up the trail but rising nearly 2,000 feet above the trailhead.  Summer hikers have trouble enough dealing with this elevation gain, but winter hikers – as we learned last year –  find it impossible without the assistance of snowshoes.  The first steep section just short of Upper Eagle Falls would prevent any further progress, leaving me with only a teasing view up the gorge and a commitment to try again on our next visit.

There was even more snow this year than last – a good 4-6′ it appeared, but our rented snowshoes made this irrelevant (even desirable), and the four of us began the arduous task of climbing the snow-laden slopes all the way up to Eagle Lake.  It was a family affair, so the pace was dictated by 10-yr old Madison, who got us to Eagle Lake – serenely beautiful and frozen solid – in a leisurely 1 hour 45 minutes.  The hike back down the gorge passed more quickly (almost too quickly) but provided spectacular views of Emerald Bay and Lake Tahoe below. Those of you with an interest in the geological history of Lake Tahoe may refer to my earlier posts, Lake Tahoe, California (Mar 2008) and Born of Glaciers (Mar 2009).  The rest of you may just enjoy these pretty pictures.

View of Upper Eagle Falls - it was here where our hike last year would end.

View back down the gorge from bridge over Upper Eagle Falls.

Looking back down at Emerald Bay from Eagle Falls Trail.

Further up the trail, one looks back upon this spectacular view of Jake's Peak.

Eagle lake lies at 8,500' elevation (frozen lake surface visible through trees left).

Copyright © Ted C. MacRae 2010

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Hawn State Park – Winter Hiking at its Finest

Two weekends ago we received another wave in what has been an unusually frequent series of snow events. I’m sure my northern (and Patagonian) friends are not impressed, but at our middlin’ latitudes snow falls rather infrequently and rarely sticks around for long when it does. This winter has been different, with snowfall almost every week, it seems like, and temperatures that have remained cold enough to keep it around for awhile. While this latest snowfall measured only a modest 1-2 inches here in the St. Louis area, a 7-inch blanket (as measured by my hiking stick) fell in the Ozark Highlands just south of here. Coming as it did at the start of the weekend, I welcomed the opportunity to go for a hike — among my favorite wintertime activities — in a landscape that is rarely seen covered in deep, newly-fallen snow. My daughter Madison loves hiking as much as I do (even in deep snow), so the two of us headed off to perhaps my favorite of Missouri’s public areas, Hawn State Park.  I have long adored Hawn for its premier hiking, facinating geology, and unusual flora, and everytime I visit Hawn I find something new to love about it.  

Lamotte sandstone outcrops on the White Oaks Trail


Such was the case on this visit, when Madison and I decided to explore the White Oaks Trail, a newer trail that I had not yet hiked.  I was a little concered whether we would even be able to get to the park, as the road leading into it had only been partially plowed (and we had already seen one car off the road, causing me to reach down and switch on the 4-wheel drive).  Most of the park was snowed in, but we were able to reach the uppermost parking area, leaving our snow-covered trail-finding abilities as the last obstacle to overcome.  After studying the trail map and looking at different route options, I asked Madison if she wanted to hike 2 miles, 4 miles, or 6 miles.  She immediately blurted out “6 miles!”, so off we went.  I was disappointed to see that we were not the first persons to have the idea, as we entered the trail only to find two sets of footprints (one human, one canid) leading off in front of us.  It did, however, make following the trail easier, and in fact I’ve had enough experience finding trails through the Ozark Highlands that I never felt like I needed the footprints in front of us to point the direction.  

Madison next to the root wad of an 83-yr old wind-thrown oak tree.


The White Oaks Trail followed nicely up-and-down terrain through mature white oak (Querucs alba) (appropriately) upland forest dissected by small riparian valleys before settling into relatively mild terrain through monotonous black oak forest.  Just when I thought the trail wouldn’t match the splendor of Hawn’s Whispering Pines and Pickle Creek Trails, it wrapped around to the south at the far end and passed by a beautiful hoo-doo complex of Lamotte sandstone outcroppingss supporting majestic, widely-spaced, mature shortleaf pines (Pinus echinata).  The rock outcrops provided a perfect spot to break for lunch while looking out on the deep, snow-covered valley in front of us.  

More Lamotte sandstone exposures along Pickle Creek, Whispering Pines Trail.


After counting a cut, wind-thrown black oak (Quercus velutinus) and determining a lifespan of 83 years, we took a connector trail down to the Whispering Pines Trail where it ran alonside the incomparably beautiful Pickle Creek.  Our hope was to hike down to the igneous shut-ins, where hard, pink rhyolites channeled the creek’s clear, spring-fed waters through narrow chutes and miniature gorges.  Upstream from the shut-ins, Pickle Creek runs lazily through the softer Lamotte sandstones that overlay those ancient rhyolites, combining with the snow cover to create a scene as peaceful and serene as any I’ve ever witnessed.

Pickle Creek meanders lazily through Whispering Pines Wild Area.

  
Just above the shut-ins, Pickle Creek bends to the west, carving deeply into the soft sandstone.  The porous nature of the rock allows moisture to trickle through and between the strata from the hillside above, creating seep zones that weaken underlying layers and lead to their collapse.  The abundant moisture this winter and continuous cycles of daytime thawing and nighttime freezes have resulted in extraordinary ice formations along the bluff face and underneath the overhanging layers, the likes of which are rarely seen in our normally more open winters.  Compare the scene in the first photo below with that in the second, taken at almost exactly the same spot one year ago in February 2009.  

Icicle formations along Pickle Creek, Whispering Pines Trail.


Same place as above in February 2009.


Ice rarely forms over the small ponds and lakes that dot the Ozark Highlands, much less its creeks and other moving waters.   The scene below of Pickle Creek as it exits the sandstone gorge is a testament to the slowness of its movements and the unusually consistent cold temperatures experienced during the past several weeks.  Only a short distance downstream, however, these lazy waters reach the bottommost layers of the erodable sandstones and encounter the hard rhyolites below.  These half-a-billion year old layers of igneous rock are much more resistant to the wearing action of water, which rushes noisily through narrowly-carved chutes before fanning out in broad sheets over smooth, steep slopes below.  

Pickle Creek along Whispering Pines Trail.


Sadly, there would not be time to visit the shut-ins.  The short February day conspired with our snow-slowed pace to leave us with a too-low-sun by the time we reached the fork in the trail that led to the shut-ins, a mile in one direction, and our car, a mile in the other.  Although we (both) had thought to carry flashlights (just in case), the last thing I really wanted to do was find myself stumbling over snow-covered trails through the dark with my 10-yr old daughter. Even had we survived the nighttime winter woods, I might not have survived the inevitable maternal reaction to such an escapade.

Arriving back at White Oaks Trailhead with a few minutes to spare.


Copyright © Ted C. MacRae 2010  

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Myths about why Lake Tahoe does not freeze

p1020598_2In my recent post, Born of glaciers, I touched on the formation of Lake Tahoe and discussed the glacial origins of Emerald Bay and nearby Fallen Leaf and Donner Lakes.  At the end of that post, I listed some interesting facts about Lake Tahoe, including the fact that Lake Tahoe does not freeze over.  That last fact was linked to one of the many internet sources explaining that Lake Tahoe’s massive size and the fact that its waters are always in motion prevent it from freezing. Sounded good to me.

Fortunately, my post drew the attention of David C. Antonucci, an environmental and civil engineer and author of the website TahoeFacts.com. David pointed out that this widely circulated explanation for why Lake Tahoe doesn’t freeze (repeated even by the U.S.D.A. Forest Service, Lake Tahoe Basin Management Unit FAQ website) is, in fact, wrong. David is currently updating his TahoeFacts.com website to include a more detailed explanation about this, but he sent me a draft of his update and has graciously given me permission to quote from it in order to help clear up some of the confusion.

As David points out, size is not the reason – Lake Baikal has more than three times the depth of Lake Tahoe and 160 times the volume, yet is freezes over to a thickness sufficient to support a railway. Nor is it the motion of the water – the Bering Sea is rocked all winter long by violent storms but still forms thick ice cover. The real reason results from a combination of three basic scientific principles:

  1. Freshwater has the unique property of reaching its maximum density at about 39°F – that is, water is densest at a temperature 7°F above the temperature at which it freezes.    For any lake to freeze, its surface waters must cool to 39°F, at which time they become denser than the underlying waters and sink beneath them.  This process continues until the water at all depths is a uniform 39°F, after which the surface waters can continue cooling down to 32°F and begin freezing.
  2. Freshwater bodies gain heat during summer when air temperatures exceed the temperature of the water at the surface and lose it during winter when air temperatures are below the water surface temperature.  The rate at which stored heat is lost during winter depends upon the surface area/volume ratio – lakes with a higher ratio (i.e., they have a large surface area compared to their volume) lose heat quickly, while those with a smaller ratio (small surface area compared to their volume) lose it more slowly.
  3. The rate at which heat is lost is also affected by climate.  Freshwater bodies in colder climates will lose heat more quickly than those with the same surface area and volume in a milder climate.

These three principles combine to explain why Lake Tahoe does not freeze over.  Lake Tahoe has a very small surface area/volume ratio due to its great depth but relatively small circumference.  This limits the rate at which stored heat is lost from the lake during the colder winter months.  The relatively mild climate that occurs in the Tahoe Basin, due to its proximity to the warm Pacific Ocean, further limits the rate at which stored heat is transferred to the air above it.  The result of all this is that the surface temperature of Lake Tahoe never reaches 39°F.  The lake is coldest in late March with a temperature of 41°F at the surface and gradually decreasing to 39°F at a depth of 500-600 ft and below.  Before the surface of the lake has a chance to cool further, increasing sunlight and air temperatures start raising the temperature at the surface.  By early May, surface temperatures reach 50°F, and they peak at 65°F to a depth of 15 ft by mid-August.  However, the summer warming penetrates only to a depth of about 375 ft – where the temperature has remained at 41°F.  Since the upper layers of water never cool below this temperature, they never sink below this depth and allow further cooling to take place.  It is, ironically, a lack of movement that prevents Lake Tahoe from freezing. In order for Lake Tahoe to freeze over, climatic conditions would have to become much colder, or the lake would have to fill in and decrease its depth enough to achieve a sufficiently high surface area/volume ratio.

David also points out that Emerald Bay has formed complete ice cover at least three times during the 20th Century and partial cover in more years. The reason for this is that Emerald Bay lacks the same depth of the main lake – its surface area/volume ratio is high enough to lose its accumulated heat and reach the required 39°F top to bottom during particularly cold winters.

Copyright © Ted C. MacRae 2009

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