10 Report on the projected Survey of the State of Maryland. 



there are others, as at upper Marlborough in Prince George's coun- 

 ty, where the banks on the western branch of the Patuxent, consist- 

 ing of gravel, sand and clay, envelope masses of a siliceous incrusta- 

 tion, containing casts of marine shells. These masses of silicified 

 shells are observed to rest on a deposite of sand and broken shells* 

 made up of oyster shells, scallop shells, Stc. A similar deposite oc- 

 curs in the neighborhood of Queen Anne, and another which has al- 

 ready acquired some celebrity in the annals of science, is that at Fort 

 Washington on the Potomac. But as the products of this last depos- 

 ite are more especially interesting to natural history than otherwise 

 susceptible of any useful application, it is not thought necessary to 

 give a particular description of them at present. The undersigned, 

 however, feel themselves bound in this place to acknowledge, in the 

 warmest terms of gratitude, the polite attentions which they have re- 

 ceived from Major Mason, of the United States' army, the comman- 

 ding officer on the station. 



They have, likewise, to return their thanks to Dr. Brereton, sur- 

 geon. U. S. army, on the same station, for specimens of various kinds 

 o{ clay obtained from that neighborhood. A partial examination of 

 these clays, led to the expectation that they might be advantageously 

 used in the manufacture of pottery ware ; and the result obtained by 

 an intelligent manufacturer in Baltimore, to whom they were sub- 

 mitted for further and more practical examination, proves them ac- 

 cordingly to be excellent materials, which are extensively used in a 

 very important branch of our manufacturing industry. Of the three 

 varieties submitted to experiment, one was found to be a very supe- 

 rior material for the manufacture of the better sorts of stone ware, as 

 well as for the ordinary pottery or earthen ware : the other two were 

 of fair quality, and applicable to the making of common pottery. 



The clay deposites, in the whole of that portion of Maryland de- 

 signated as belonging to the tertiary o,rder of geological formations, 

 offer a subject of investigation of the deepest interest to several branch- 

 es of the manufacturing classes of the state. This formation may be 

 described as extending, so far as this state is concerned, over the 

 whole eastern shore of Maryland, south of a line drawn from east to 

 west through Cecil county, commencing at the Delaware line, pass- 

 ing a few miles north of Elkton, and terminating a few miles below 

 Port Deposit on the Susquehanna. If the same line be continued 

 from a point a little above Havre de Grace, on the opposite side of 

 the Susquehanna, through Harford and Baltimore counties, with ve- 



