Morrow Mountain State Park, NC. Image ©Andy Bobyarchick.
High Rock Lake is one of several impoundments on the Yadkin-Pee Dee river system in the North Carolina Piedmont. Flat Swamp Creek is, or was, a tributary to the Pee Dee River. After the High Rock reservoir filled Flat Swamp Creek became a narrow, northeast-trending arm to the larger lake. …
Ripples are periodic waveforms throughout the natural environment. These subaqueous asymmetrical wave ripples in sand under the Pee Dee River in North Carolina are created by oscillatory wave motions normal or slightly oblique to the shoreline.
Needle ice forms in porous, wet soil or sediment when the soil temperature is above freezing and the surface atmosphere temperature is below freezing. Permeability is important. Capillary action pulls water up toward the surface where the water freezes at the bases of growing ice crystals. The growing crystals are capable of lifting small particles and vegetation above the normal soil surface. This differential motion can thoroughly disaggregate and disrupt the upper several centimeters of the soil profile in temperate climates.
The images in this gallery were made in an elementary school yard where patches of bare soil are exposed. By the time I walked over the yard, the sun had melted most of the crystals except for those protected by shadows. Most of the single, larger grains on top of the crystals are coarse sand, perhaps around 2 mm (millimeters) in diameter.
All photographs in this post ©Andy R. Bobyarchick.
Carter, J. R., 2013, Flowers and ribbons of ice: American Scientist, v. 101, p. 360-369.
Li, A., Matsuoka, N., and Niu, F., 2017, Frost sorting on slopes by needle ice: A laboratory simulation on the effect of slope gradient: Earth Surface Processes and Landforms, p. <xocs:firstpage xmlns:xocs=””/>. 10.1002/esp.4276
Li, A., Matsuoka, N., and Niu, F., 2018, Frost sorting on slopes by needle ice: A laboratory simulation on the effect of slope gradient: Earth Surface Processes and Landforms, p. n/a-n/a. 10.1002/esp.4276
Soons, J. M., and Greenland, D. E., 1970, Observations on the Growth of Needle Ice: Water Resources Research, v. 6, no. 2, p. 579-593. 10.1029/WR006i002p00579
Yamagishi, C., and Matsuoka, N., 2015, Laboratory frost sorting by needle ice: a pilot experiment on the effects of stone size and extent of surface stone cover: Earth Surface Processes and Landforms, v. 40, no. 4, p. 502-511. 10.1002/esp.3653
Needle ice in a loamy soil in a schoolyard near Salisbury, NC. The individual particles on top of the needles are coarse sand in size. Needle ice forms when soil water moves upward under capillary pressure and freezing when it contacts cold air. I will be posting a gallery of images with context on my blog soon. (The server is having intermittent problems right now.)
“Tectonic” as an adjective or “tectonics” as a noun refers to the large-scale structure of Earth’s crust and lithosphere. Outside of geology, the word tectonic may refer to a building or construction. The concept arrived in geological sciences prior to “plate tectonics”, mainly with application to mountain building. The word …
Well, you have to start somewhere, don’t you? This isn’t the beginning. It’s just a place in time, or maybe a coordinate in space-time, when the world around you seems gigantic. The hill is a mountain, the ground is a rolling ocean of green. We are ultra cool with a …
I lack enough creativity to distribute my photographs in some intelligent way, so you can find a number of photo albums on my Facebook page. Here’s a current list of the main albums below. The links will transport you to the relevant album. Many of the images don’t have much …
More or less. There were posts to an earlier version of the Geologist’s Pick back when it was partly designated to service a university-level class. (See the Colophon for a little history.) That was before Facebook, Twitter, and the tsunami of social media onto our shores. This site – it’s …