( 319 ) 



No. L. 



Observations to serve for the Minerabgical Map of the Slate of 

 Maryland. By M. Godon. 



Read November 6th, 1807. 



ALLUVION SOIL, 



All the country which extends from Baltimore bay, to the 

 right bank, of Potomac river, where Washington city is situ- 

 ate, is wholly alluvial. The soil which constitutes it is, in 

 general, a quartzose sand, diversly coloured by iron. This sand 

 very frequently contains mica; aluminous earth also appears to 

 exist in it, in a very small proportion. It is probably to the 

 want of a sufficient quantity of clay in this alluvial ground, 

 that the remarkable barrenness of the land which stretches on 

 the line that I have occasionally travelled, must be attri- 

 buted. 



At some distance under the surface of the soil, a bed of 

 quartzose white stones is frequently found. This bed is hori- 

 zontally disposed, or appears to follow the inequality of the 

 ground. 



Immediately under this bed of flint, a stratum of a ferru- 

 ginous sand-stone commonly occurs, the thickness whereof 

 varies from six lines to one foot or more. This mineral, 

 the only one which is found, or which can be expected 

 to be found in this soil, deserves a particular examination, on 

 account of its importance as it regards the geology of this loca- 

 lity. It is most commonly compounded of quartzose grains ; 

 sometimes of flakes of mica. Its tenacity at times is very 

 great, but most frequently it is disunited with ease by the 

 stroke of the hammer. 



It sometimes includes concretions of a strongly ferruginous 

 clay, analogous to those stones, which, though, a variety of iron 

 ore, are vulgarly known by the name of antes, or eagle-stone. 

 These concretions are almost always involved in thin con- 



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