138 THE ECONOMIC RESOURCES OF CALVERT COUNTY 



greater age of the deposits, although also represented in the Wicomico 

 and the Talbot. 



THE GRAVELS. 



The Pleistocene formations contain numerous beds of gravel widely 

 distributed throughout the region. They occur in pockets or lenses, 

 either immediately at the surface or but thinly covered by the sands and 

 loam. In the latter case they can be seen in many places outcropping 

 along the valleys. These gravel deposits have only been used to a small 

 extent in this section although similar deposits in the vicinity of Wash- 

 ington have been extensively worked. As ballast for roads they possess 

 considerable value and will doubtless be extensively used in the future 

 in the building of permanent roads throughout the county. They are 

 probably inferior in value to the igneous rocks yet serve their purpose 

 well when properly used. They are generally rich i a iron, which acts 

 as a cementing agent, although there are many places where the gravels 

 lack this desirable material. In such cases it is necessary to add ferru- 

 ginous sand or clay to bind them together. The most extensive surface 

 gravel deposits are located near Bowens and Ferry Landing. The gravels 

 range in size from coarse sand to pebbles several inches in diameter. 



THE BUILDING STONE. 



Although the formations of the county are composed almost entirely 

 of unconsolidated materials, yet locally indurated beds are not uncom- 

 mon. In the absence of any better stone these indurated ledges furnish 

 considerable material for the construction of foundations and well walls. 

 At Mackall, near the mouth of St. Leonard Creek, there is a firm ledge 

 of Miocene rock which has been utilized for such purposes. Elsewhere 

 ferruginous sandstones and conglomerates from the Pleistocene deposits 

 supply the small local demand for rough building purposes. 



TLIE MARLS. 



The Eocene and Miocene formations of the State are rich in deposits 

 of marl which are of value as fertilizers. From New Jersey to North 

 Carolina these deposits have been spasmodically worked since the early 



