MARYLAND GEOLOGICAL SURVEY 131 



latter is the principal use to which it is put. It has been thought that 

 the diatomaceous earth might be of use in certain branches of pottery 

 manufacture, which require on the part of the materials refractoriness 

 and an absence of color when burned. Dr. Heinrich Ries tested a sample 

 of the diatomaceous earth from Lyons Creek at cone 27 in the Deville 

 furnace and found that the material fused to a drop of brownish glass. 

 The non-refractory character of the diatomaceous earth is thus clearly 

 demonstrated. It is also used in the manufacture of fire and heat- 

 retarding ccnients and fire-proof building materials, such as solid brick 

 and hollow brick for partition walls and floors. 



Not all of the diatomaceous earth of the region is valuable, some con- 

 taining an excessive amount of sand. At Lyons Creek wharf it is quite 

 pure and has been worked for a number of years by the ^Mar^-land Sili- 

 cate Company. The deposit is about 20 feet in thickness at this point. 

 The output of the Lyons Creek locality long exceeded that of any other 

 region in the United States and put Maryland at the head of the diato- 

 maceous-earth producing states. The average value is about $5000. It 

 varies greatly, however, in different years because of the varjdng demand 

 for the material, and partly because of the production of a supply in 

 some years sufficient to meet tlie trade demand for several years in 

 advance. Because of the liniitod deniaiid for it and the considerable 

 number of states in wliicli diatomaceous earth is found it is improbable 

 that the industry in Calvert County will ever reach very large proportions. 



The Water Resources. 



The available water resources of Calvert County include the surface 

 streams, natural springs, and the dug or driven wells. In the absence of 

 large towns or great industries where large amounts of water are re- 

 quired, the streams have not been utilized for water-supply purposes. 

 In fact, it is doubtful if they could ever be depended tipon for potable 

 water because of the large amount of vegetation which they contain 

 during the summer months and the liability to contamination from the 

 run off of the adjoining cultivated lands. In some instances dams have 

 been constructed and the power utilized by small manufacturing con- 



