ART. 26 REMAINS OF FOSSIL. POEPOISES — KELLOGG 5 



The sedimentary record of the Calvert formation has been dis- 

 cussed by Shattuck " in an article entitled " The Geology of Calvert 

 County," from which the following is quoted : 



The close of the Nanjemoy epoch was marked by an elevation of the region 

 whicli brought the Eocene deposits above the ocean and exposed them to a 

 prolonged attack of erosion. After the region had suffered extensively from 

 the work of waves and rivers, it was again submerged beneath the ocean and 

 the material composing the Calvert formation were deposited. As the Miocene 

 sea advanced little by little on the sinking surface of the mainland, the waves 

 caught up and reworked the clays and greensands of the various Eocene beds. 

 Tlie more obdurate fossils of the Eocene survived in a great measure the 

 erosive work along the old Miocene shore and were carried out and deposited 

 in deeper water. They may now be seen reworked in the basal member of 

 tlie Calvert formation. The old shore line of the Miocene sea which was 

 formed during the Calvert epoch of sedimentation has nowhere been preserved 

 in Maryland, but the materials which composed the Calvert formation in this 

 county were deposited in seas of moderate depth in which an abundance of life 

 was present, as is sho>vn by remains of diatoms and the extensive beds of 

 fossil mollusks. The remains of whales and other cetaceans show that these 

 vertebrates abounded in the ocean, and the discovery of a bone belonging to a 

 gannet indicates that birds existed along the near-by shores. This particular 

 form doubtless sought its food in the sea as the modern fishing gannets do at 

 the present time. 



The Calvert epoch was brought to a close by the elevation of the region once 

 more above tlie level of the ocean. A period of erosion followed which was 

 probably of short duration and closed with the depression of the region again 

 beneath the sea. Then followed the deposition of the Choptank and St. Mary's 

 formations, in which conditions similar to those just described for the Calvert 

 were repeated. 



In spite of the process of erosion that must have been going on for 

 a considerable period, remarkable exposures of the Calvert forma- 

 tion exist to-day along the western shore of the Chesapeake Bay. 

 These cliffs, which extend along the western shore of the Chesapeake 

 Bay from Chesapeake Beach southward to the mouth of the Pa- 

 tuxent Kiver, a distance of about 35 miles, consist mainly of clays 

 belonging to the division of the Maryland Miocene known as the 

 Calvert formation. This area has been very carefully examined and 

 described by the Maryland Geological Survey which has published 

 a full account of the characteristics of the several superimposed 

 strata or zones and of the molluscs contained in each. 



It is a comparatively easy matter, therefore, to locate quite exactly 

 the relative position of the various cetacean bones found in the cliffs. 

 The Calvert cliffs have long yielded specimens of different species 

 of toothed and whalebone whales, the former belonging to several 

 different families and genera. 



Near the base of zone 10 and in zone 4 oysters are present in large 

 numbers. From this it would appear that a barrier beach had been 



"Shattuck, G. B., Calvert County, Maryland Geological Survey, Baltimore, pp. 106- 

 107, 1907. 



