1892] MARYLAND ACADEMY OF SCIENCES. 211 



explanation as the result of mountain bnilding movements. 

 Its unbroken axis is a stiff, although uneven, ridge of mas- 

 sive clay. Upon and against this have been built far less 

 coherent strata of sand, sandy clay, lignitic clay, narrow 

 belts of plastic clay, and a heavy stratum of disintegrated 

 rock, in the condition of moderately loose sand. Ignoring 

 the local bed of greensand marl, we find next above its 

 level a bed of coarse gravel mixed with sand, in which 

 piles of boulders contribute to the immense weight. Over 

 all of this is heaped up a thick body of sand, which bears 

 on its surface, especially upon the ridge, numerous granitic 

 boulders, each of many tons weight. Possibly all of this 

 material above the granitic sand constitutes an average 

 thickness of twenty feet. 



Such an enormous load of heavy material, accompanied 

 by the thrust and pressure of ice-bergs driven over the 

 surface and stranded at intervals, even if an extended 

 glacier did not exert its energy upon this weakly con- 

 solidated elevation, might well have disturbed the poise of 

 its upper beds, and opened clefts to the attacks of the rains 

 and the frosts. A small amount of faulting has occurred 

 within recent years, evidently occasioned by the down- 

 ward pressure of the upper beds. Cracks, like the most 

 landward of the successive series present on the upper 

 surface of this promontory, are common on many parts of 

 the cliffs of Chesapeake bay, and when these are attacked 

 by the thaws and rains of early spring, they open widely, 

 and either precipitate the outer portion upon the beach, or 

 start it to sliding down the slope. Where such exposures 

 are open to the storm-driven surf, the cliffs are under- 

 mined, and the overlying material either slides or falls 

 according to its steepness and tenacity. 



All of the strata below the greensand marl, that are 

 found in the Vineyard Series, occur more or less flexed in 

 New Jersey and Maryland ; but in no locality, thus far 



