HOLMES] DOWLIXG FAR>r QtlARRV-SHOP 69 



All important villagosite occurs on tlic high terrace overlooking the 

 iioitliern end of the bridge, fornieriy occu|)ied by Freeman's greeu- 

 houses. now the property of the Baltimore and Ohio railway company, 

 and another site yielding great numbers of relics is situated on the 

 Donaldson place, high above the river on the southern side. 



In June, 1890, my attention was called to a series of chipped stones 

 obtained Ironi the farm of Thomas Dowling, about a mile above Cabin 

 John bridge and S miles from Washington. The collection was made by 

 Thomas Dowling, junior, and included many of the rude forms common 

 on the qnarry-.shop sites already examined, as well as a number of well- 

 flnished implements. During a visit to the locality it became apparent 

 that this was an ordinary shop site, which bore also considerable evi- 

 dence of having been occupied for dwelling. The site is a hundred yards 

 beyond the J)owling gate, on a terrace, the summit of which is about 

 20 feet above the Conduit road and 1 GO feet above the Potomac. Back 

 of the terrace, which is but a few acres in extent, the hills rise gradually 

 to their full height of some 350 feet above the river. The surface of 

 the terrace is somewhat uneven, and is covered with rocks of varying 

 sizes, including many bowlders and masses of quartzite with irregu- 

 larly shaped remnants of other varieties of stone. Much of this mate- 

 rial was utilized by the aborigines. It is to be noted that the available 

 material supplied by this site does not correspond closely to that of the 

 great quarry sites of Eock creek. The hills above furnish but few work- 

 able bowlders until we go far back from the river. During the early 

 Pleistocene Columbia jieriod these lower terraces were subject to river 

 overflow and thus received accessions of bowlders and fragments of 

 rock from the u[)-river country, but this material is inferior, both in 

 quantity and in (puility, to that of the Potomac formation. It does not 

 ap])ear that extensive quarrying was carried on in this locality, as 

 the deposits would not warrant it. 



ANACOSTIA VALLEY 



The estuary of Anacostia river varies from one-quarter to three- 

 quarters of a mile in width in its lower course, but just above Ben- 

 niiigs bridge it becouies quite narrow. It is bordered for the most 

 part by low alluvial terraces which rise from the water to the base of 

 the slopes of the plateau, here reaching nearly 300 feet in maximum 

 height. Ill places low blufl's composed of Columbia gravels ajiiiroach 

 the river banks, and in the angle between the Anacostia and the 

 Potomac the Columbia formation occurs in terraces varying from a 

 few feet to nearly 100 feet in altitude; on these in the main the city of 

 Washington is built. 



The only members of the Columbia formation of particular interest 

 in this study are the bowlder-bearing gravels. These are extensively 

 exposed in iilaces, and in the vicinity of the navy-yard reach a thick- 

 ness of 20 feet or more, though the bowlders are not generally suited 

 to the use ot the implement maker. Tiiey are often of quartzite and 



