PLANT LOCALITIES. 13 



Oil tlio riglit l)aiik of tlio canal ami in the thin interstratifiecl layers of 

 sand and clay a curious mode of occurrence of plants was discovered. In 

 examining hero the clay layers, to procure as large specimens of Diounitrs 

 as possible, a small mass of pale reddish i)lastic clay was found embedded in 

 the interstratified sand and dark gray clay. This reddish clay seemed to 

 be a ball inclosed in the stratified material. It was without bedding, and 

 was somewhat contorted and affected with slickensides. From this it will 

 be seen that its lithologic character differed totally from that of the matrix 

 in which it was inclosed. The fossils found in it showed still greater differ- 

 ences, for the large impressions of Diooititcs Buchianus were lacking, and 

 instead there was a great variety of plants, some of which have not been 

 found anywhere else. A number of the species occurring in this homoge- 

 neous clay seem to have been delicate, finely incised ferns, some of which 

 were beautifully preserved. This mass seems to have been a fragment torn 

 off from some bed of clay exceptionally rich in plants, which was subsc- 

 (juently embedded in the interstratified sand and clay. The number and 

 beauty of the impressions found in it make special reference to it desirable. 

 It will be referred to as "Red clay ball, Dutch Gap Canal." This clay mass 

 was five to six feet in diameter. The locality in general will be character- 

 ized as "Dutch Gap Canal.'' By this will be meant that the plants thus 

 referred were found in the banks of the canal, but not in the red clay 

 ball. 



Above the canal thei-e is a reach of river about one and a half miles 

 long. The left bank for this distance is mostly high, and composed of Qua- 

 ternary resting on Potomac. J\Iost of tlie Potomac material is a gray, 

 coarse, current-bedded sand, with here and there pebldes and large clay 

 balls. In places in the sand, nearl}' at high-tide level, are lenticular layers, 

 interrupted patches, and irregular masses of both dark gray and reddish 

 clay, the former predominating. These are undisturbed. Plants are found 

 in several places, mostly in the lenticular layers and interrupted patches of 

 gray clay. The cla}' is very tenacious and plastic, with indistinct cleav- 

 age. It is difficult to work out good specimens from it, notwithstanding 

 the undisturbed condition of the material. The plants, however, are pre- 

 served in it very perfectly. 



