114 THE ECONOMIC RESOURCES OF ST. JIART'S COUNTY 



the region and, in a few instances, have furnished materials for the 

 manufacture of brick. They are not suitable for pottery or the finer 

 grades of brick but make a fairly good variety of common red brick. 

 Since the clay supplies are ample there seems to be no good reason why 

 the county should not produce all the livick and tile of this character 

 required for local uses. Should a ready market be found and better 

 means of transportation obtained, brick for shipment might perhaps be 

 produced at a profit. However, since other counties in the State more 

 favorably situated with respect to markets and the main lines of railroads 

 contain equally extensive clay deposits, sometimes of a better quality, it 

 is not probable that St. ilary's County will ever become an important 

 clay center. It should, however, produce enough brick to supply the 

 local demand. 



Should the experiments that are being tried elsewhere of using burned 

 clay for road metal prove to be successful some of the clay of the county 

 may be profitably used in this way. Since the sandy roads seriously 

 interfere with the development of the region there will undoubtedly be 

 an increased demand, sooner or later, for cheap road metal, and it is 

 possible that the clay of this region may partially meet this demand. 

 The clays occur in deposits of both Tertiary and Quaternary age. 



Tertiary Clays. — Although argillaceous beds occur very frequently 

 in the Miocene and Lafayette strata of the State, in general they are too 

 sandy to be of much economic importance. 



The Calvert, Choptank, and St. Mary's formations of the Miocene all 

 contain beds of sandy clay which are well exposed in many places along 

 the Patuxent Eiver and in the other stream valleys. The Calvert, which 

 outcrops in the northwestern portion of the county, contains more of this 

 clay than do the other Miocene formations, and the clay is less sandy. 

 It is bluish-green to black when fresh, but becomes lighter in color on 

 exposure. It has never been worked and is probably of little economic 

 value because of its large percentage of sand, iron, and lime. The lime 

 is derived from the numerous fossil shells which are either generally 

 distributed throughout the sandy clay or massed in definite shell beds 

 within it. 



