MARYLAND GEOLOGICAL SURVEY 103 



a thickness of 33 feet has been observed. In other places the formation 

 has been found to thin down and disappear. Its average thicloiess for 

 the county is about 15 feet. 



Character of Materials. 

 The materials which compose the Talbot formation consist of clay, 

 loam, peat, sand, gravel, and ice-borne boulders. These, as a rule, do 

 not lie in well-defined beds, but grade into each other both vertically and 

 horizontally. The coarser materials, with the exception of ice-borne 

 boulders, are usually found with a cross-bedded structure, while the 

 clays and finer materials are either developed in lenses or are horizontally 

 stratified. The ice-borne blocks are scattered throughout the formation 

 and may occur in the gravel beneath or in the loam above. There is 

 distinguishable throughout a tendency for the coarser materials to occupy 

 the lower portions and the finer the upper portions of the formation, 

 but the transition from one to the other is not marked by an abrupt 

 change. The coarser materials are frequently found above in the loam 

 and finer materials below in the gravel. They also show less decay than 

 in the other surficial formations. Within the Talbot formation there 

 are a number of lenses of drab clay, bearing plant remains. The most 

 important of these are situated one mile north of Drum Point on the 

 shore of the Patuxent River, about a mile below the mouth of St. Leon- 

 ard Creek. These have been discussed at length in the succeeding 

 chapter. They will, therefore, not be considered here except to say that 

 the locality north of Drum Point yields, in addition to vegetable re- 

 mains, fragments of fossil insects. 



Stratigraphic Relations. 

 The Talbot formation is deposited as a terrace lying unconformably 

 and somewhat irregularly on the older beds of Eocene and Miocene age. 

 This terrace was laid down about the margin of the Wicomico forma- 

 tion and locally is believed to lap up on the thin eroded edges of the 

 latter which are supposed to run out a short distance beneath it. It is 

 usually separated from the Wicomico formation by a well-defined scarp. 



