Maryland Geological Survey 33 



general similarity has made it impossible to establish distinctive floras 

 as a basis for the correlation of the several formations, and their dis- 

 crimination has been based mainly on physiographic grounds. 



The materials consist of clay, loam, sand, gravel, peat, and ice-borne 

 boulders. These do not occur as a rule in very definite beds, but grade 

 into each other both vertically and horizontally. The coarser materials 

 are often cross-bedded, and are for the most part confined to the lower 

 portion of each of the formations, while the finer materials, particularly 

 the loam, are commonly found in the upper part of the formations, 

 although these conditions are by no means universal. Each of the 

 formations rarely exceeds 25 feet or 30 feet in thickness, although under 

 exceptional conditions a thickness of two or three times that amount 

 occurs. 



Recent 



The Eecent deposits embrace chiefly those being laid down to-day over 

 the submarine portion of the Coastal Plain, and along the various estu- 

 aries and streams. To these must also be added such terrestrial deposits 

 as talus, wind-blown sand, and humus. In short, all deposits which are 

 being formed to-day under water or on the land by natural agencies 

 belong to this division of geological time. 



The Recent terrace now in process of formation along the ocean 

 shore-line and in the bays and estuaries is the most significant of these 

 deposits, and is the latest of the series of terrace formations which began 

 with the Lafayette, the remnants of which to-day occupy the highest 

 levels of the Coastal Plain, and which has been followed in turn by the 

 Sunderland, Wicomico, and Talbot. 



A deposit of almost universal distribution in this climate is the humus 

 or vegetable mold, which being mixed with the weathered surface of the 

 underlying rocks forms our agricultural soils. The intimate relation- 

 ship, therefore, of the soils and underlying geological formations is evi- 

 dent. 



Other accumulations in water and on land are going on about us all 

 the time, and with those already described represent the formations of 

 Eecent time. 



