PLANT LOCALITIES. - 15 



These localities embraoe all tliat are worthy of mention in the vicinity 

 of Dutch Gap. The narrow neck of land tln'ough which tlie canal is cut, 

 and which is known as Dutch Gap, is by river 17 miles below Richmond; 

 by country roads, 12 miles. 



In the interval between Richmond and Fredericksburg- no plant-im- 

 pressions have been found, and in the immediate vicinity of the latter town 

 only one place has yielded any notable amount of fossils. As was stated 

 before, this spot was discovered b}- Professor Uhler. 



The plant-bearing layer at I'redericksburg, on being- followed in fi-om 

 the outcrop, proved to \)e very limited in horizontal extent. The space 

 from which impressions were obtained was only about fifteen feet square, 

 and the fossiliferous material seemed to be a lenticular pocket, apparently 

 formed in an edd}- in tlie waters. On the outcrop the impressions were 

 more numerous and better preserved than farther in. The particular layer 

 that most abounded in vegetable matter served as a water-way, and the 

 long-continued seepage of water through it destroyed much good material. 



The locality now in (piestion is situated just below Mr. Phillips's ware- 

 house and near the boat-house of the Fredericksburg boating club, on 

 the right-hand side of the road descending to the steamboat landing. 

 When first seen Ijy me the fossiliferous material was exposed in the form 

 of a small ledge of rock close to the road. The ledge was mainly com- 

 posed of a gray, highly argillaceous, and very fine-grained sandstone, 

 graduating into sandy shale. About four feet of the material contained 

 vegetable matter. The u])per portion for about three feet contained few 

 I'ecognizable parts of plants, while it had in a layer of considerable thick- 

 ness so nuu'h connninuted plant-matter that it was colored brown and ren- 

 dered thinly fissile. Nearly all the good impressions occurred towards the 

 bottom of the mass, near its junction with a bed of cobble-stones, on -which 

 the fossiliferous stratum rested. 



Distinct impressions were found mostly in a la\er here three tt) five 

 inches in thickness. This cobble-stone bed is one of the most curious 

 features of the locality. It thickened up so as to cut out in all directions 

 the plant-bearing material. The cobbles are composed of Azoic rock, such 

 as occurs several miles to the west of the spot, mixed with some rounded 



