6 TRANSACTIONS OF THE 



At three miles below Lewistown, are exposed nu- 

 merous seams of fine greenish brown sandstone, sepa- 

 rated as before, by thin courses of micaceous clay and 

 shale, containing some magnesia. So numerous are the 

 beds of fucoides here, that eight or ten were counted within 

 the space of six feet ; some of which did not exceed an 

 inch in thickness. Lower down the narrows succeeds 

 a group of argillaceous and ferruginous beds; whose 

 upper surfaces were covered with obscure forms, and 

 irregular branching protuberances, probably derived 

 from some other species of fossil algae. 



November 11 th and 12th, The exploration of the 

 fucus beds was resumed, and from it results the disco- 

 very of a series far more extensive than had been con- 

 templated. On the margin of the canal, at the western 

 end of Shade Mountain are exhibited numerous seams, 

 varying from an inch to a foot in thickness, of argilla- 

 ceous sandstone, the superior faces of which were ob- 

 served to be thickly covered with obscure fuci or algae. 

 These seams are separated by partings of soft argilla- 

 ceous rock, and greenish or yellow clay, from half an 

 inch to an inch thick, almost entirely composed of ac- 

 cumulated plants of the same description. An opening 

 or quarry made in this series exhibits an astonishing 

 succession of vegetable surfaces or growths. At least 

 one hundred courses are distinguishable within a per- 

 pendicular section of only twenty feet, all of them 

 crowded with fossil plants of the obscure kind, and oc- 

 casionally crossed by the larger fucoides. 



At another point as many as twenty layers of fucoides 



