JAMES RIVER SECTIONS. 



77 



Fig. 1. — Dutch Gap Canal. Diagrammatic representation of the east bank. 



IV. Section on Dutch Gap Canal. 



Feet 

 Pleistocene 1. Argillaceous sand grading down into gravel 20 



2. Cobble bed 5 



Lower Cretaceous. Patuxent 3. Coarse, arkosic gray sand with numerous peb- 

 bles, clay pellets, and clay balls. The latter 

 are barren dark drab clay or hard brown clay 

 or somewhat sandy brown clay with leaf 

 impressions. Occasional lenses of sandy 

 brown clay, indistinctly laminated carry good 

 leaf impressions including Acrostichopteris 

 parvifolia Font. Acrostichopteris pluripar- 

 tita (Font.) Berry, Arthrotaxopsis grandis 

 Font., Cladophlehis oblongifolia Font., Cla- 

 dophlebis distans Font., Cladophlehis Broion- 

 iana (Dunk.) SeAvard, Dioonitcs Buchianus 

 (Ett. ) Born., Dryopteris dentatuni Font., 

 Dryopteris macrocarpum Font., Leptostrubus 

 foliosus Font., Nageiopsis longifolia Font., 

 Nageiopsis zamioides. Font., Onychiopsis 

 Goepperti (Schenk) Berry, Osmunda sphe- 

 nopteroides Font Scleropteris elliptica Font., 

 Sequoia Reichenhachi (Gein) Heer, Sphenole- 

 pis Kurriana Schenk, Thyrsopteris hrevi- 

 folia Font., Thyrsopteris brevipennis Font., 

 Thyrsopteris dentata Font., Thyrsopteris 

 divaricata Font., Thyrsopteris obtiisilobata 



Font., and Zamites tenuinervis Font 0-9 



4. Dark drab stratified, pyritiferous and lignitic 

 clays 0-6 



Total 26-3 



Above the lower entrance to the canal along the right bank of the old 

 river channel the Potomac Group is exposed more or less continuously for 

 a distance of between 3 and 4 miles as far as the Howlett House bluff. At 

 this point the following section is seen: 



