MARYLAND GEOLOGICAL SURVEY 139 



similar in all four formations, has been extensively used for the 

 manufacture, of brick at many places in Virginia, the District of 

 Columbia, Maryland, and southeastern Pennsylvania. It is gener- 

 ally not more than 3 or 4 feet in thickness, 3-et, because of its posi- 

 tion, many beds no more than 1 or 2 feet thick can be worked with 

 profit. The loam is widely distributed throughout the county and, 

 though not quite coextensive with the formations of which it forms 

 a part, it is present in almost every locality where the Lafayette 

 and Pleistocene formations occupy flat divides that have not suffered 

 much erosion since their deposition. In general the surface loam 

 is adapted only to the manufacture of the common varieties of brick 

 and tile, but in some places it is suitable "for making a fair quality 

 of j)aving brick. In this region the surface loam from the Talbot 

 and Wicomico formations has been utilized at several different times 

 for the manufacture of brick in the eastern part of Washington, near 

 Anacostia River. 



THE SANDS. 



Inasmuch as the arenaceous phase predominates in almost every 

 Coastal Plain formation represented in the region. Prince George's 

 County contains an unlimited supply of sand. The sand of the Pleis- 

 tocene and Lafayette formations is used locally for building purposes, 

 but as it is so readih' obtainable in all parts of the region no large 

 pits have been opened. 



In some places the quartz sands of the Miocene seem to be pure 

 enough for glass making, suggesting the Miocene glass sands so 

 extensively exploited in southern ISTew Jersey, although they have 

 never been used in that way in this region. Careful chemical analy- 

 ses and physical tests, which have not been made, would be required 

 to determine their usefulness in this industry. 



The Magothy sands in the vicinity of Anacostia have long been 

 worked and at present the most extensive sand pits of the region are 

 opened in deposits of this age a short distance south of Anacostia. 

 The sand is used for building and filtering purposes. In certain 



