Home Archive by category "geology"

Category: geology

An Upland Bog in North Carolina

This upland bog lays on the top of a mountain ridge in Uwharrie National Forest, NC. The ridge top is unusually flat, possibly caused by the weathering and erosion characteristics of underlying metamorphosed volcanic rocks or it is an old terrace created by the Pee Dee River, that is west of this location. The only drainage outlet is a small low-order ephemeral stream and the stream's head is elevated above the level of the bog. There is also a geomorphic barrier on one side of the ridge created by a resistant rhyolite layer. Two deer ran across the bog as I approached.
This upland bog lays on the top of a mountain ridge in Uwharrie National Forest, NC. The ridge top is unusually flat, possibly caused by the weathering and erosion characteristics of underlying metamorphosed volcanic rocks or it is an old terrace created by the Pee Dee River, that is west of this location. The only drainage outlet is a small low-order ephemeral stream and the stream’s head is elevated above the level of the bog. There is also a geomorphic barrier on one side of the ridge created by a resistant rhyolite layer. Two deer ran across the bog as I approached.

Ripples over Bedrock № 1

ripples over bedrock 21
Shallow water ripples over jointed bedrock with algae.

Water ripples are forming in very shallow water of a Piedmont stream as it flows over orange bedrock. The rock is a metamorphosed argillite (fine-grained sedimentary rock) whose present color is the result of weathering in an oxygen-rich environment. Algae has grown preferentially in planar, nearly vertical fractures in the rock called joints.

The stream is in Uwharrie National Forest, North Carolina.

Image © Andy R. Bobyarchick.

Amanita section Lepidella in Uwharrie National Forest, NC

This gallery contains 7 photos.

These are images of mushrooms from the Uwharrie National Forest in Montgomery County, North Carolina. The fungi are from the genus Amanita (Basidiomycetes > Agaricales > Amanitaceae). The bulbous stem base and other features put these in Amanita section Lepidella. I have not attempted to determine a species. These are…

Continue reading

Meander and Point Bar in Flat Creek, SC

Flat Creek southeasterly through Lancaster County, South Carolina. The stream feeds into Lynches River, that farther southeast joins the Great Pee Dee River. The Pee Dee joins the Waccama River at Georgetown on the SC Atlantic Coast.

Flat Creek carries a heavy load of sediment. Where this image was made, the stream crosses the Pageland granite, a pluton that is about 300 million years old. The granite is coarse-grained and sheds considerable quartz and feldspar grains as it weathers and erodes.

This image is a 180° panorama around a meander bend in Flat Creek. Lower water velocity on the inside of the meander causes the coarser sediment load to drop out to form a sandy point bar. The near bank of the river is being undercut by erosion on the outside of the meander where water velocity is greater. In time, the stream channel will migrate toward this cut bank.

It’s difficult to see in the shadows, but in the lower left corner of the photograph a tributary trickles into the main channel, and there are abundant beaver tracks there. Beavers use the tributary mouth as a slide.

In the lower right corner of the photograph you can see a boulder of Pageland granite. It’s rounded shape is characteristic of spheroidal weathering of a larger mass of granite bedrock.

Not far to the southeast, Flat Creek crosses from Piedmont igneous and metamorphic rocks into sedimentary rocks of the Sandhills.

This image was made late on a Spring afternoon under a brilliant blue sky reflecting off the water’s surface and under the long shadows of hardwood trees yet to put out theire leaves.

This image is ©Andy R. Bobyarchick

meander and point bar

A meander bend and point bar in Flat Creek near Taxahaw, SC.

Sand and Ripples in the Pee Dee River

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.

shoreline features on the Pee Dee River, Morrow Mountain State Park, NC

Sand bar, shore line, subaqueous ripples and tree stump on the Pee Dee River, Morrow Mountain State Park, NC. This photograph ©Andy R. Bobyarchick.