14 THE PUTOMAO OE YOUNGER MESOZOIO FLORA. 



The most important locality in this reach, and the one which has 

 yielded the most numerous and best preserved specimens found at Dutch 

 Gap, is situated a few yards above a spot used by fishermen as a landing 

 place for their reel nets, where a small shanty is located. Where the plants 

 are obtained two layers of dark gray clay occur in the base of the bluff, 

 a foot or so above high tide. These layers are undulating in their course 

 and tend to run together. Where most distant from each other, they are 

 separated by eighteen inches of sand. Plants occur irregularly in both 

 layers, but in the lower seam there is a portion, only two to three inches 

 thick, that contains plant-impressions for a considerable distance. 



This fossiliferous seam is usually found near the center of the clay layer, 

 but it rises and falls in its course, so that it is sometimes near the top and 

 sometimes near the bottom. ' The clay layers are each about twelve inches 

 thick, but they vary a good deal. Tlie lower layer is much the richer in 

 impressions. The best specimens of Equisetum found in the Potomac for- 

 mation occur at this spot, also very fine specimens of Dioonites. Many coni- 

 fers, especially long-leaved Sequoias, a number of ferns, good impressions 

 of Baieropsis pJuriimrtita minor, and a number of other plants may here be 

 obtained. The locality will be referred to as " Fishing hut above Dutch 

 Gap Canal." 



About two hundred yards above this spot there is a pocket of dark 

 clay in the sand, which stands at so low a level as to be covered by high 

 tide. This is full of leaves of Dioonites quite well preserved, but, as is 

 usually the case when the Dioonites is abundant, only few other species 

 occur. About one and a half miles above the canal a very large spring 

 discharges into the river, at a place called Sailor's Tavern. The clays and 

 sand found farther down the stream still continue to show themselves for 

 about four hundred yards above the spring in the form of an irregular 

 bluff. About two hundred and fifty yards above the spring a pocket 

 of gray clay, irregularly mixed with sandy matter, occurs at about high- 

 tide level. This material, when it was first found, was carefully exam- 

 ined, and tlie impression of the posterior part of a fish was obtained from 

 it. Above this point on the river no good plant-impressions were found. 



