Maryland Geological Survey 35 



Eichard C. Taylor, in a paper immediately following that of Mr. 

 Clemson devotes six pages and a folded plate to the description and 

 illustration of these plants, which he identified as Lycopodiolithes ? sp., 

 Lepidodendron sp., Sphenopteris sp., Pecopteris f sp., and Thuites ? sp., 

 and which are the remains of Frenelopsis, Sphenolepis, Cladophlehis, etc. 

 These he saw bore no relation to the plants from the Richmond coal 

 field, which were attracting considerable attention at that time and he 

 infers that the containing rocks are of Secondary age, perhaps co-eval with 

 the oolites. 



The year 1835 also marks the beginning of the important series of 

 reports on the geology of Virginia by William B. Eogers, State Geologist 

 of that State, the first describing the Potomac sandstones along the 

 " Fall-line " and mentioning the presence of siljcified wood, lignite, and 

 plant impressions. In his report for 1839 the same author traces his 

 " Sandstone formation " as far south as Boilings Bridge on the Fottaway 

 Elver in southern Virginia. In his next report, that for 1840, he desig- 

 nates this formation the " Upper Secondary," and traces its extent 

 northward from Petersburg to the Potomac Eiver. Later reports also 

 frequently refer to these rocks, which he regarded as Upper Oolite in age. 



Eichard C. Taylor returns to this subject in his work on the Statistics 

 of Coal, published in 1848, and compares the organic remains to those 

 from the Portland of southern England. 



With the appointment of Philip T. Tyson to be State Agricultural 

 Chemist of Maryland, the latter State enters the literature. The map 

 accompanying his first report enumerates twenty-four formations, of 

 which the Cretaceous includes two, the first " a thick group of sands 

 and clays of various colors." " In some localities it abounds in lignite 

 derived from coniferous plants." " The bluish-gray varieties derive their 

 color from the carbonaceous remains of plants"; the second, or Iron-ore 

 clays, " a series of beds of fine gray and lead-colored clays containing 

 several courses of carbonate of iron in flattened masses and nodules." 

 " The color of these clays is due to carbonaceous matter." 



Tyson early discovered a saurian tooth in the latter beds, which was 

 described under the generic name Astrodon by Christopher Johnston in 



