86 



At the base of the cliff there is a five foot bed of very black 

 carbonaceous clay. It is in the lower portion of this bed just at 

 tidal level that the cypress stumps are located. This part of 

 the bed is tightly interwoven with the roots and knees of the 

 cypress stumps, so much so that in places they form a solid 

 wooden floor. This bed extends in an east-west direction for 

 about a hundred feet and then disappears under the sand of the 

 beach. The upper surface of the bed is very irregular for there are 

 in two places evidence of old stream channels. These channels 

 were cut from 1—3 feet deep below the surface and they have 



Fig. 1 Showing section and cypress stumps at Greenbury Point, Maryland 



a width of several feet. They are now filled with very coarse 

 iron stained quartz sand. On the weathered surface of this bed 

 and for a depth of about 2 inches below the surface one finds 

 botryoidal aggregates — up to f inches in diameter — of vivian- 

 ite. Vivianite is a hydrous ferrous phosphate which is often 

 found in cavities of fossil bones and in such swamp deposits as 

 described herein. This mineral after it is partly oxidized is a 

 very intense blue turning duller as oxidation progresses. 



During my first visit to this locality I found in this lower 

 bed three poorly preserved casts of Unios. These fossils are in 



