| Photo Information |
Copyright: Bob Harrison (BobH)
![Silver Star Critiquer/Gold Note Writer [C: 41 W: 8 N: 192]](http://i1.treknature.com/misc/s-n-g.gif) (638) |
| Genre: Landscapes |
| Medium: Color |
| Date Taken: 2005-11-02 |
| Categories: Savannah |
| Camera: Olympus 700C UZ |
| Photo Version: Original Version |
| Date Submitted: 2007-11-28 17:18 |
| Viewed: 1621 |
| Points: 4 |
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| [Note Guidelines] Photographer's Note |
Many transcontinental air routes across the US afford excellent views of unusual natural features. Most people rely on the pilots for notification and identification, which is spotty at best and usually limited to the more spectacular features. This picture definitely is not in that category, but is nonetheless quite interesting. The under-the-radar nature of the subject is actually my primary reason for choosing it- based on my experience over the years, most people have never heard of or seen the Sand Hills. Furthermore, since most of the landscapes on TrekNature are ground level, this post provides a unique perspective of a unique place.
This composite photo of two aerial shots shows two very different aspects of the Sand Hills region in north central Nebraska. As for my earlier aerial photo post of the merging glaciers, I've never visited at ground level. I read about this area many years ago in National Geographic and have kept it in mind all that time because it is so unusual and interesting- and nearly unpopulated. When I realized we would be flying over it (Boston to Denver), I kept my camera at hand and was well rewarded.
The Sand Hills are an attractive subject because of their uniqueness, including a wonderful visual texture from the air. The region is especially intriguing because nature remains dominant here, even though the surrounding Great Plains have been highly modified by modern agriculture. That contrast between natural and modified is the theme of this pair of pictures.
More on that contrast after some background information, very slightly edited from Wikipedia (http://en.wikipedia.org/wiki/Sand_Hills_%28Nebraska%29 [Nov. 28, 2007]).
The Sand Hills is a region of mixed-grass prairie in north-central Nebraska, covering just over one quarter of the state (more than 50,000 kmē). The World Wide Fund for Nature designated the Sand Hills as an ecoregion, distinct from other grasslands of the Great Plains. According to their assessment, as much as 85% of the Sand Hills ecoregion is intact natural habitat, the highest level in the Great Plains. The reason is primarily due to the lack of agriculture. Most land in the Sand Hills has never been plowed.
The plant-anchored dunes of the Sand Hills were formed at the end of North America's most recent ice age by wind-blown particles originating from regions to the north and west of Nebraska. At several times in the past 10,000 years, during periods of extreme drought, the Sand Hills have been active sand dunes; however, this has not happened since around 1400 A.D. The mixed-grass prairies supported large populations of bison until the 1870s.
Back to my own notes on the aforementioned contrast. The left frame shows the Sand Hills region at its wildest. The only clear sign of human presence is the road snaking across the dunes. The region has many small ponds, but none appear in this view. As is common with aerial shots, vertical scale is hard to determine, but the dunes obviously pose a formidable barrier to both agriculture and travel. Various references say their height may reach 100 m. The left frame shows sand exposed in many places, suggesting that the covering soil is both thin and fragile. The poor nutrient content of such soil would likely doom any attempt to plant conventional crops. Across the top right a river course is clearly defined by the bottom land vegetation, still green in early November, even at nearly 1000 m elevation.
The right frame was shot roughly 200 km to the west and shows the the dunes giving way to agriculture on the fringe of the Sand Hills region. There is abundant groundwater (the Ogallala Aquifer) and it enables farmers to plant more than just dryland crops. The dominant feature of this shot is the orthogonal arrangement of roads and fields so familiar to anyone traveling over or through the midwest US. Horizontal scale is given by the standard half mile (800 m) diameter center pivot irrigated field, the tan circle at top left. The two dark brown squares touching corners in the middle right are the same width. This image captures the transition zone from the dunes of the Sand Hills to the conventional agriculture of the high plains part of the midwest. Just a few miles further west were swaths of hundreds of tangent circles, each one a half mile diameter center pivot irrigated field like the one in this photo.
The most surprising aspect of the right frame is the degree to which the texture of the dunes is visible despite the intensive agriculture. I have no idea about vertical scale in this photo, and I would love to know more if anyone can comment knowledgeably. Are the dunes still visible on the ground, or is it necessary to be flying above to see them? As a scientist, I know that major variations such as this are theoretically possible just based on soil quality, subtle drainage differences, and other factors not visible from the air. But it's hard to believe the land is totally flat- it seems that some residual dune topography must also be involved in the striations captured in this image.
Tech photo notes:
As for my earlier aerial photo post, shooting through a commercial airliner window is far from ideal and that portion of my earlier comment also applies here.
Both shots were brightness adjusted and had a LOT of contrast added, as seems to be the norm for anything shot under these conditions. This is due mostly to the amount of atmospheric haze, but airplane windows can sometimes be a big problem also.
Slight sharpening in Photoshop was used on the left frame, but there is some irreparable fuzziness across the middle of both frames due to jet exhaust.
Note added 12-3-07
This link (http://apnews.myway.com/article/20071128/D8T6U9V00.html) is to a story about CNN founder Ted Turner and the recent increase in his land holdings in the Sand Hills. According to the article, "Turner owns the largest buffalo herd in the country, 45,000 strong, many of them on the 425,000 acres (172 000 hectares) he owns in Nebraska." |
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