Thursday, November 12, 2009

The Earth is Falling

The GAC crew conducted a one-day site examination on an early 19th-century domestic site in a neighboring county earlier this week. It proved instructive in that it represents the exact opposite effect of erosion that we see in Port Tobacco.

In Port Tobacco, large expanses of the town are covered in sediments that had eroded from the surrounding uplands. But what do you suppose archaeological sites in the uplands look like?

The site we looked at this week had been plowed earlier in the year. We found nothing on the surface of the high ground, although we did note two pieces of pearlware on the low ground several hundred feet to the west and northeast. Fifteen shovel tests at 25 ft intervals on three parallel transects produced only sparse traces of brick. Metal detecting produced only two handwrought nails and one machine-cut, machine-headed nail. Five 3 ft by 3 ft test units yielded five sherds of pearlware, some small oyster shell and brick fragments, and another handwrought nail. Clearly there is an early 19th-century domestic site on this small ridge.

Two of our test units exposed part of an ash-filled pit (see above). Note the ring around the perimeter that I scored with my trowel, showing the bottom sediment encompassing a later deposit. We estimate that we recovered half of the pit and that it was at least 4 ft in diameter. A small test hole near the presumed center revealed that it was only three inches deep. We excavated the exposed portion of the pit and it proved to be uniformly shallow.

My reading of this pit feature is that it has been heavily truncated by plowing and erosion. An estimate of one to three feet lost to erosion seems reasonable...the sparse artifacts in the overlying plowzone support this estimate. The site has eroded away and only the very bottom portion of a deep pit has survived. If you were to have stood upon this site a century ago, my guess is that you would have been one to three feet higher in elevation. Where did all that soil go? Take a look at the nearby creek and the answer becomes obvious.

Based on work elsewhere, I think this erosional problem has plagued Southern Maryland for years, but it greatly accelerated with the widespread adoption of motorized plowing beginning in the 1930s.


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