280 PROCEEDINGS OF THE AMERICAN ACADEMY 



while devoted to academic pursuits, he had shown such an interest in 

 geological studies that he was in 1818 appointed by the senate to suc- 

 ceed Hailstone as Woodwardian Professor of Geology to the University, 

 a post which, with his fellowship, he held till his death. Thenceforth 

 his energies were chiefly given to the duties of his new office, and to the 

 advancement of the science which it had become his duty to teach. In 

 1819 he aided in the formation of the Cambridge Philosophical Society, 

 in the Transactions of which appeared, in 1820-21, his earliest contri- 

 butions to geology, being researches on the crystalline rocks of Corn- 

 wall and Devon. These were soon followed by studies of the magnesian 

 limestones of the north of England, which occuj^ied him from 1822 to 

 1828, and constitute one of the most important contributions to geo- 

 logical science of their time. He also visited Germany for the purpose 

 of studying there the corresponding strata which are intermediate 

 between the coal formation and the Meseozoic, and constitute the 

 series to which Murchison afterwards gave the name of Permian. 



It was about this time that Sedgwick became acquainted with 

 Murchison, who, having left the army, was devoting himself as a 

 zealous and successful amateur to the study of geology, and soon became 

 the disciple and fellow-laborer of the Cambridge professor. Together 

 they visited Scotland in 1827, and the eastern Alps in 1829 and 1830 ; 

 and in 1831 undertook with a common plan, but separately, the great 

 work of investigating the rocks of Wales beneath the old red sand- 

 stone. These ancient strata and their equivalents of the continent, 

 at that time almost unstudied, were then included under the com- 

 mon name of the Gray wacke series ; and to the two investigators 

 just named belongs the honor of having first clearly determined 

 their stratigraphical and paleontological historjr. The labor of Sedg- 

 wick in North Wales soon enabled him to make out a great series of 

 strata, to which he gave the name of Cambrian ; while Murchison, 

 at the same time working fi'om the south-east border of Wales, 

 recognized a series to which he gave the name of Silurian, placing 

 it above the Cambrian of Sedgwick. That the lower divisions of 

 this were identical with the upper portions of his Cambrian was 

 soon pointed out by Sedgwick; but the confusion between the two 

 was only cleared up by the discovery that the sections of Murchison 

 were erroneous, he having confounded under the name of Cambrian 

 two series of strata of different ages. The one in Salop was the same 

 with the lower Cambrian of Sedgwick, and really below the base of 

 Murchison's lower Silurian ; while the other in South" Wales, instead of 

 being, as supposed, beneath it, was really but a repetition of the latter, 



