Providing deep benefits to the deep Pocomoke River

Deborah Painter (USA)

The famed English explorer of the “New World”, Captain John Smith, led expeditions during the early 1600s to create charts and plan settlements along the east coast of the United States, from what is now Virginia to Maryland and, on a subsequent voyage, New England. Smith’s map of coastal Maryland shows the Pocomoke River, as well as some Native American villages.

This area of the eastern shore of the Chesapeake Bay north of the Virginia line remained mostly rural for many centuries and was used for farming, timber production and the smelting of iron from an impure form of iron known as “bog iron” (ferrous oxyhydroxides, mixed with limonite and goethite). The area is still mostly rural, with scattered towns and one rapidly growing small city. Pocomoke City is just over the Maryland border from Virginia and not far from Wallops Island Flight Facility, a National Aeronautics and Space Administration launch facility just 37km distance.

The vast Pocomoke River State Park and the Pocomoke State Forest on the Bay side of Maryland’s Eastern Shore are well known for cypress swamps that border the Pocomoke River. The river originates in the Great Cypress Swamp in Delaware and flows south-westerly 106km to the Chesapeake Bay. For a coastal plain river, the Pocomoke has an unusual number of tight turns and is the deepest river for its width (approximately 30.1m at its deepest point) in the world (Fig. 1). It is a maximum of 13.71m in depth.

Fig. 1. Vantage point on the Pocomoke River Bridge in Maryland looking upstream from Business Route 13 (Market Street) toward the Route 13 Bypass. (Credits: Deborah Painter.)

Geological history

To know why the river is so deep, it is necessary to go back in time, to the Wisconsin glacial maximum of the Pleistocene epoch. A mosaic compiled in 2008 by geologists Wayne L Newell and Inga E Clark furnished LIDAR-based digital elevation geomorphic analyses of new macro-topographic details of the Delmarva Peninsula (named for Delaware, Maryland and Virginia) and other portions of the Mid-Atlantic region of the United States.

The geologic ages studied include late Cenozoic to recent sediments from fluvial, estuarine, and littoral depositional environments. Extensive, thick Pleistocene sandy dune fields were deposited over much of the terraced landscape of what is now eastern Maryland. The LIDAR image depicts two meter-scale resolution of details of the shapes of individual dunes, and fields of sand sheets, which were shifted from one location to another.

Many terraces have preserved the histories of elliptical or circular rimmed basins that are prehistoric ephemeral ponds repeatedly formed, drained and overprinted by younger ponds. These landform details, and the erosional and depositional details, were interpreted by Newell and Clark to be the effects of the drier, colder climate of the mid-Atlantic region during the Wisconsin Glacial Maximum.

In addition, LIDAR revealed sandy floodplain remnants, with formerly diverging channels that had later merged into others to form a smaller number of channels. The warming climate of the end of the Pleistocene brought about increased precipitation. More precipitation brought about more vegetation growth, which stabilised the dunes. More precipitation also resulted in more flow into streams, which caused them to cut their beds deeper. The Pocomoke is one of those streams.

Damage by humans

Humans deepened some of the narrower sections still further. A section of the river was channelized in a dredging operation in the 1940s upstream and north of Pocomoke City, paid for by locals concerned about navigation after ice trapped a buyboat loaded with lumber for weeks at Pocomoke City at one of the narrowest points.

The depth is 7.3m there and the width is 30m. Such dredging caused oxygen depletions. And the dredged material was placed, as was the custom in decades past, in berms from one to three meters high along both banks. This created a host of ecological and flood management problems, destroying fish, wading bird and duck habitat, making sheet flow from the floodplain and the uplands further impeded, and increasing flooding downstream.

Restoration

Beginning in 2012, 21 local landowners teamed with the US Geological Survey, the US Natural Resources Conservation Service, the US Fish and Wildlife Service, and private organisations including the National Fish and Wildlife Foundation, the France-Merrick Foundation, and Ducks Unlimited (Fig. 2). Over one hundred cuts have been made in the berms within this 14km channelized section in the largest ever ecological restoration effort in Maryland.

The US Fish and Wildlife Service has furnished a LIDAR-based map of the restoration project shown in Fig. 2.

Fig. 3. This LIDAR-created digital elevation map shows the artificial channel in the portion of the Pocomoke River shaded in green in Figure 2 as well as shoals and ancient dune fields. (Credits: US Fish and Wildlife Service.)

Fig. 3 shows the artificial 1940s-era channel and elliptical, closed features occurring in the riverbed itself and in the floodplain and uplands.

Once believed to be “Carolina Bays”, which do occur in eastern Maryland, these features have been analysed in the field, both in upland and in salt marsh areas. They have the signature ridge and furrow topography and the closed basins of dune fields. Carolina Bays are also elliptical depressions, but they have other features that distinguish them from dune fields that make them a mystery to this day, since no single mode of origin can explain them.

The picturesque Market Street (Business Route 13) bridge over the Pocomoke at Pocomoke City is a highlight of a trip to this community. It is the shortest steel and concrete span over a waterbody that this author ever walked across (Fig. 4).

Fig. 4. The Pocomoke River Bridge at Business Route 13. (Credits: Deborah Painter.)

There are many places along the seawall here to peacefully contemplate the surroundings of the mostly serene riverfront (Fig. 5).

Fig. 5. On a sunny day mid-week, visit the Pocomoke River at Pocomoke City to be afforded much peace and quiet. (Credits: Deborah Painter.)

On the south bank is a city park that is rather soggy in many spots (Fig. 6), and on the north bank is the rural community of West Pocomoke and the Pocomoke State Forest.

Fig. 6. There are tennis courts and many wet areas at Cypress Park along the Pocomoke. (Credits: Deborah Painter.)

A natural history museum, the Delmarva Discovery Center, is located at 2 Market Street next to the old bridge at Pocomoke City (Fig. 7).

Fig. 7. A side visit to the Delmarva Discovery Center can yield a pleasant and educational diversion, highlighting the Pocomoke and the general area. (Credits: Deborah Painter.)

Here, a full-sized steamship is partially reproduced. One can climb “aboard” (Fig. 8) and see how small the captain’s bathtub and sink would have been, and can stand next to the “wheel” inside the “wheelhouse” and “pilot” the boat using a video that moves in accordance with the motion of the wheel (Fig. 9).

Fig. 8. The Delmarva Discovery Center includes a mock steamship. (Credits: Deborah Painter.)

Fig. 9. Once “aboard”, visitors can pilot the steamship with a wheel and a computerised simulation. (Credits: Deborah Painter.)

In the Center are displays of:

the kinds of tools used by the oyster boats downstream of Pocomoke City;
an Eastern oyster and an Atlantic Ocean surf clam, such as those found at the Pocomoke’s mouth and beyond (Fig. 10);
a display of the many uses of cattails by the locals;
a touch tank;
live otters;
a live snapping turtle and soft-shell turtle (Fig. 11); and
mounted fish found in the Pocomoke, including the important commercial fishes known as shads and a mounted longnose gar (Fig. 12) – a very interesting member of a family of ray-finned North American fish that have changed little since the Cretaceous period. Longnose gars grow to a bit less than one meter in length at maturity.

Fig.10. Eastern Oyster (left) and Atlantic Ocean Surf Clam (right) shells. (Credits: Deborah Painter.)

Fig. 11. A live female soft-shell turtle. (Credits: Deborah Painter.)

Fig. 12. Longnose gars are common large sport fish in the waters of the Pocomoke River. (Credits: Deborah Painter.)

Bog iron

The mining and processing of the bog iron from the nearby wetlands at Snow Hill to the east of Pocomoke City lasted from 1830 to 1849 (Fig. 13). Bog iron is low grade iron, and the demand for it began to decrease after just under two decades. As a result, the factory “town” was abandoned to the surrounding forest to be restored 127 years later and turned into an open-air museum. This is open several days a week, currently Thursdays through Sundays in the spring through the autumn. It is located at 3816 Old Furnace Road, Snow Hill.

About the author

Deborah Painter is an ecologist and general environmental scientist. She lives in the United States.

References

Cintos.org The Enigmatic Carolina Bays page: The Enigmatic Carolina Bays (cintos.org).

Delmarva Discovery Center: Delmarva Discovery Museum l Pocomoke City, MD (delmarvadiscoverycenter.org).

Furnace Town Website: Virtual Village Tour — Furnace Town Historic Site.

Newell, Wayne L., and Inga E. Clark. March 7, 2008. Geomorphic map of Worcester County, Maryland, interpreted from a LIDAR-based, digital elevation model. U.S. Geological Survey 2008-2005.

Pheiffer, Thomas H., Daniel K. Donnelly and Dorothy A. Possehl. August 1972. Water Quality Conditions in the Chesapeake Bay System. Technical Report 55. Environmental Protection Agency Environmental Planning Branch, Air and Water Division, 248 pgs.

Rasmussen, W.C., and Slaughter, T.H., 1955, The groundwater resources In: The water resources of Somerset, Wicomico, and Worcester Counties by Rasmussen, W.C., Slaughter, T.H, Meyer, R.R., Bennet, R.R., and Hulme, A.E., State of Maryland Department of Geology, Mines and Water Resources, Bulletin 16, 170 pgs.

Geological history

Damage by humans

Restoration

Bog iron

About the author

References

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