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THE GEOLOGY OE CALVERT COUNTY 



time, the waves along the shore had an opportunity to do considerable 

 erosive work and forced the shore lines back toward the rivers, widening 

 the valleys which had been previously opened during the erosive interval 

 which followed the uplift of the Sunderland formation. The material 

 which was derived from the wave erosion was deposited along the floor 

 of these estuaries, filling them in to a considerable extent and raising 

 them up to a higher level than that which they possessed when the 

 country was submerged at the beginning of the epoch. While this pro- 

 cess of sedimentation was still in progress, the country once more rose 

 above the level of the waves and permitted the streams to cut again in 

 their old valleys. This epoch of elevation was apparently a short one 

 for there was not enough time to enable the streams to completely re- 

 establish themselves throughout the entire length of their former valleys. 

 They had only partially begun the erosive work when the country was 

 once more submerged beneath the waves and the deposition of the Talbot 

 terrace was begun. At this time, the streams were once more transformed 

 into estuaries, but not to the extent which they were in the previous 

 Wicomico cycle of deposition. The land did not sink more than 45 feet 

 below its present altitude and remained there for only a short time when it 

 was once more raised and eroded. This epoch of elevation was the one 

 which ushered in the present cycle of events and permitted the cutting 

 of the Eecent sea-cliff. Since its initiation, the land has once more as- 

 sumed a downward motion, and the entire coast line in this region seems 

 to be sinking once more beneath the level of the waves. 



Along the shore of Chesapeake Bay and the lower courses of many 

 of its estuaries there occur at intervals deposits of greenish-blue clay 

 developed as lenses in the body of the Talbot formation. Usually the 

 base of the clay is not visible but its stratigraphic relations are such as 

 to leave no doubt that it, or a thin gravel bed on which it occasionally 

 rests, is uncomformable on whatever lies beneath. The upper surface 

 of these clay lenses is everywhere abruptly terminated by a bed of coarse 

 sand or gravel which grades upwards into loam and at its contact with 

 the clay strongly suggests an unconformity. These clay lenses are in 

 some localities devoid of fossils but in others they contain remains of 



