

williamk] THE ROGERS BROTHERS, B. SILLIMAN. 49 



from Canada to the sources of the Mississippi. The Paleozoic was rec- 

 ognized in its distribution throughout the eastern part of the United 

 States. The Coal Measures were recognized in Pennsylvania, Ohio, 

 Indiana, Illinois, Michigan, and Missouri. The Devonian was recog- 

 nized by some of its fossils in New York State, but its- limitation was 

 not determined precisely as at present. The Silurian had been recog- 

 nized in at least the Caradoc sandstone, the Weulock shale and lime- 

 stone, and the Ludlow rocks, but it was not until the final reports were 

 published (two or three years later) that a full classification of the 

 Paleozoic series was accessible to American geologists. 



The Kogers brothers used fossils to determine the age of the Mait- 

 land limestone, and concluded that " though they indicate relation to 

 Onondaga, Seneca, and Marcellus strata, the exact age is not proven." 

 In other respects these authors adopted the New York classification as 

 a standard for comparisons. 



The "Address before the Association of American Geologists and 

 Naturalists for the year 1842 n was given by B. Silliman. 1 



In it we have a few indications of the state of the science at that 

 time. Silliman had the advantage of being in England in 1805, when 

 the discussions of the rival schools, the Neptunists and the Vulcanists, 

 the Wernerians and the Huttouians, were at their height ; Prof. Jame- 

 son and Dr. John Murray defending the Wernerian views, and Sir 

 James Hall, Prof. Playfair, and Prof. Thomas Hope defending the 

 views of Hutton. Silliman appears to have taken a neutral position in 

 regard to these schools, recognizing the good points of each. We find 

 a statement made in the course of his description of his part in the prog- 

 ress of science that Dr. Dana read the title of what was probably the 

 first geological report made on American geology, at the meeting of 

 the Association in Boston, viz : u Beytriige zur mineralogischen Kentniss 

 des Ostlichen Theils von Nordamerika und seiner Gebirge, von D. 

 Johann David Schopf." 



Of William Maclure he said : 



He was the William Smith of this country, and not only did ho add to the foreign 

 collections of this country in mineralogy and geology, but lie did great service in the 

 direction of personal field-work and interpretation of our geology, and also in pub- 

 lishing his Geology of the United States with the first general map of the geology of 

 the eastern part of the continent. 



Mineralogy was studied prior to the cultivation of geology in 

 America as well as in Great Britain. The earlier geologists were mineral 

 geologists, and the collections of minerals constituted the principal 

 cabinets of that time. Prof. Cleaveland, of Bowdoin, Maine, Dr. Sey- 

 bert, In Philadelphia, Colonel Gibbs, at Yale College, the Messrs. Dana, 

 in Boston, had each accumulated more or less valuable mineral cab- 

 inets, and a Journal of Mineralogy and Geology was started in New 



1 Am. Jour. Sci., vol. 43, pp. 217-250. 



Bull. 80 4 



