452 EOCENE MARL. 



marl, and also in the upper part of all the other eocene marls since 

 known elsewhere in Virginia. Without reference to these, or to 

 some other characteristic shells, the eocene marl might not always 

 be distinguishable by its texture or general appearance from the 

 miocene. And even these two shells, the most abundant and 

 characteristic of the eocene formation generally, are neither to be 

 found in the lower layers of any bed that I have been enabled to 

 examine. 



For some years after the first discovery and application of this 

 calcareous eocene marl on Coggins Point farm, it was not known 

 to exist elsewhere. For even where then visible, and at later times 

 used, its different character was neither known nor suspected by 

 its proprietors. As chance furnished to me opportunities of seeing 

 the beds, or as small specimens of the marl were sent to me for 

 examination, I gradually came to know the greater extent of this 

 bed. It is now known at various points in an area of about twelve 

 miles in length, from east to west, and eight or ten miles wide, 

 which area takes in parts of the counties of Prince George (which 

 has much the larger known portion), Charles City, and the lower 

 point of Chesterfield. And in this area also is the broad bed of 

 James river, and the lower parts of its tributaries, Appomattox 

 river, and Bailey's, Powell's, and Herring creeks. The marl is 

 exposed to view on the southern side of James river, at the fol- 

 lowing several points : Coggins Point, Maycox (a mile below, and 

 the most eastern exposure as yet known), Tarbay, Wm. H. Harri- 

 son's farm, and Beaver Castle, all above on the river Eelbank 

 and Hawksnest (the most southern exposure), on Powell's creek 

 the Old Court House tract and Spring Garden farm, both on Bai- 

 ley's creek, and the latter from one to two miles above the head 

 of its tid, and three miles south of the Appomattox where oppo- 

 site. The last is the most western exposure. On the northern 

 side of the Appomattox, it is seen in the river bank at Bermuda 

 Hundred, and north of James river, and of Herring creek, at 

 Neston and Evelynton. 



Through nearly all this large area, this bed of marl preserves 

 remarkable uniformity of appearance, texture, chemical character 

 and composition, and even of the thickness of the stratum, and 

 of the succession and variations of character of the several smaller 

 layers of the general body. The bed lies nearly horizontal, but 

 dips slightly and irregularly eastward and northward. At Coggins 

 Point, its lower part is 10 to 12 feet above high tide, while at 

 Maycox, a mile to the east, and at Evelynton, three miles north, it 

 is lower than high tide mark. Yet not so much difference of ele- 

 vation as this is seen in all the greater extension westward to 

 Bermuda Hundred. The stratum varies from 4 to 10 feet thick, 

 being thinnest at its south-western exposure, Spring Garden, 



