Over the river, through the woods…down to the coast

Just two days after spending an extended weekend in coastal Massachusetts, I journeyed to the Blue Ridge in western Virginia with my family. There, we hiked a gorgeous trail along Skyline Drive and afterwards dined on delicious food in nearby Staunton. (What’s a geology adventure without food?).

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The Blue Ridge Mountains. Photo credit to L. Shawler

Jones Run trail in Shenandoah National Park traverses over 1000 feet in elevation change (unheard of to a coastal geologist!) and just under 2 miles overland, snaking along a ridge and then descending rapidly towards a topographic low along Jones Run, a mountainous creek with a steep set of waterfalls. Along the way I couldn’t help but compare this landscape to the heavily glaciated landscape of northern Massachusetts and New Hampshire which makes up the watershed at the field site for my research project. Unlike the till and bedrock that make up much of the New England landscape, the Blue Ridge ladnscape at Jones Run is covered in a relatively thick layer of loose soil except where Jones Run itself carves into the landscape, exposing abundant bedrock. The smaller creek we crossed along the trail was full of cobbles and boulders that had eroded from the higher slopes, being transported down river during fast, strong flows.

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My brother and I at the top of the Jones Run falls. Photo credit L. Shawler.

Jones Run eventually merges with Doyle’s Run, turns southeast where it joins the larger Moorman’s River. The Moorman’s River dog-legs northwest and contributes to the Mechums River, which becomes the South Fork of the Rivanna River, leading to the mighty James River. The James journeys past Richmond and down to the coast, debouching at the Chesapeake Bay. (For more on the Mechum’s River check out Prof. Chuck Bailey’s series on his trek down the Mechums, Rivanna, and James Rivers.)

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My brother and I along the Jones run trail. Notice the thick layer of soil on the landscape, likely contributing to the sediment load reaching Virginia’s coast. Photo credit C. Shawler

The James has a higher sediment load than the Merrimack in Massachusetts (100+ mg/L vs 5mg/L). Robert Meade lead a famous study comparing the sediment loads of East Coast rivers in the US. Meade’s data indicate that the glacially stripped landscape of the Northeast is starved of sediment, reducing the ability of New England rivers to input sediment to coastal systems. This means, that if we do notice anthropogenically derived changes in sediment supply at Joppa Flats, they’ll perhaps be less pronounced because the watershed already has less sediment to transport to the Flats.