wiLLiAMsl CONRAD, HUBBARD. 45 



time strenuously fought, has beeu entirely superseded. Attempts to 

 fetter the progress of science by holding on to established systems are 

 always to be avoided, and those who have the interests of true science 

 at heart should jealously watch against the prejudices which tempt 

 them to cling to those things which have been, merely because they 

 have been. 



In 1840 Conrad published a paper " On the Silurian system, with a 

 table of strata aud characteristic fossils." l This paper appears to be in 

 its essential features the same as the table published in the fifth annual 

 report of the State of New York in the following year. He had studied 

 the Silurian system of Murchison and found spread over the greater 

 part of New York, Ohio, Indiana, Kentucky, and Tennessee, and 

 terminating on the south in the mountains or hill regions of north 

 Alabama, rocks which represented the Silurian system. He reported 

 in the vicinity of Florence and Tuscumbia, Alabama, the "Oriskany 

 sandstone." At Blossburg, Pennsylvania, the "Old Ked sandstone" 

 was recognized by the presence of Holoptychius. On the western 

 slopes of the Appalachian he found the Carboniferous system well 

 developed, with the Mountain limestone rare and generally in thin 

 deposits. The "New Red sandstone" was recognized in very limited 

 areas. No traces of the u Oolitic," the "Lias," or "Wealden" were 

 recognized. The " Cretaceous" was widely distributed and the 

 u Tertiary formation" was reported as occurring on the sea border. 



In New York State the "Llandeilo flags" were recognized and the 

 "Caradoc sandstone" was regarded as the equivalent of the " Trenton 

 limestone." The " Wenlock shale " was recognized in the " Rochester 

 shale" and the "Calciferous slate" of Eaton. The " Wenlock lime- 

 stone" was identified in the "Helderberg limestones," six of them. 

 The " Ludlow rocks " were not defined in this paper. A table is given 2 

 showing the characteristic fossils of each of the formations and their 

 English equivalents as represented in Murchison's Silurian system. 

 This paper is particularly interesting as the first exhaustive attempt to 

 correlate the formations of America with those of Murchison's Silurian 

 system by means of their fossils alone. Previous attempts had been 

 made by him to correlate the New York rocks with the English rocks 

 in general. 3 



In a notice, by O. P. Hubbard, of the third annual report on the 

 Geological Survey of New York, 4 a few remarks are made which show 

 the confusion which existed at this time regarding the classification of 

 the New York rocks. He shows that there was considerable difference 

 of opinion as to the position of the rocks in central and western New 

 York. " They have been alternately described as Transition and Sec- 

 ondary." "The Saliferous group" is counted as above the coal series, 



» Am. Jour. Sci., vol. 38, pp. 86-93. 

 'Ibid., pp. 89,90. 

 » See New York annual reports. 

 ♦Am. Jour. Sci., vol. 39, pp. 95-108. 



