396 ORGANIC REMAINS ALONG THE 



five or six miles lower than the Little Falls above 

 Georgetown. It is just at the head of tide-water, which 

 rises and falls between four and five feet in the Eastern 

 branch. Along the shore from the mouth of Rock 

 creek to the Tiber, the land adjoining the Potomac is 

 of considerable elevation. From the latter place to the 

 point at which the junction takes place with the Eastern 

 branch, the shore is more flat and low. From this plain 

 on the south, and from the bank of the Tiber on the 

 west, rises the Capitol Hill. 



The height of this hill is more than eighty feet above 

 tide- water, and between sixty and seventy above the ad- 

 jacent low ground. Digging has shown that all the strata 

 are horizontal ; and the pebbles and stones mingled with 

 the sand are rounded as if worn by water. This ap- 

 pearance is universal along the banks of the rivers and 

 the streets. 



Under this mass of alluvial materials organic remains 

 exist. They lie in a stratum of muddy clay. Trunks 

 and branches of trees are found in abundance at the 

 depth of fifty-four feet under the surface of Capitol Hill. 

 Frequently the wood is blackened so as to resemble coal, 

 and is mingled with pyrites. 



Forty-five feet below the surface of the lower ground, 

 near the Eastern branch, a bough of sound and seasoned 

 black-walnut was found on digging a well. A bone, 

 apparently a rib of some very large, or elephantine ani- 

 mal, was dug out of the bank of the Potomac, and exhi- 

 bited for a show. Shark's teeth, or glosso-petrae, are 

 often raised on digging wells, further down the river, 

 as at Diggas's point, for example. 



