

148 THE CAMBRIAN. [bull. 81. 



Small beds of limonite are found in the Knox sandstone and Knox 

 shales. 1 In 1878 the same writer published an outline of the geology 

 of Alabama accompanied by a map of the State, based upon that of 

 Tuomey, published in 1858. Of the age of the metamorphic rocks he 

 says that until further examination he leaves the question of age au 

 open one, except in two instances, in which he believes at least a part 

 of them are metamorphosed Silurian beds. 2 



The classification and general description of the formations is essen- 

 tially the same as that contained in the reports of 1874-75. 



In a report on the physico-geographical and agricultural features of 

 Alabama, Prof. Smith notes the character of soil produced by the rocks 

 of the different formations, from the Potsdam to the Coal measures. 3 

 This paper was also printed in a general description of the State of 

 Alabama, in vol. 6, of the Tenth Census. 4 



A brief description of the Cambrian rocks of Alabama is given by 

 Prof. Eugene A. Smith, in a report on the geological structure and de- 

 scription of the valley region adjacent to the Cahaba coal field. 5 A 

 summary of it is given in the description of the Cambrian rocks of 

 Alabama. 



Keterences are made to the geology of Alabama, in a general way, 

 by Dr. T. S. Hunt, Prof. Smith, and various mining engineers, but I 

 have not, with the exception of the preceding notice, met with original 

 contributions to the knowledge of the Cambrian rocks, since the pub- 

 lication of Prof. Smith's detailed description. 



PALEONTOLOGY. 

 NORTHERN APPALACHIAN DISTRICT. 



The first discovery of fossils in rocks, now referred to the Lower 

 Cambrian, was made by Dr. Asa Fitch. 6 In the summer of 1844 he 

 found trilobites in a black slate in Washington County, New York, 

 which was referred by Dr. E. Emmons to the Taconic slate or Argillite 

 (1 of Eaton). Dr. Fitch sent the fossils to Dr. Emmons, who described 

 from them two species of trilobites under the names of Atops trilineatus 

 and Elliptocephalus asaphoides. 1 Believing that the rocks in which the 

 trilobites occurred were unconformably beneath the Potsdam sandstone, 



1 The iron ores of Alabama, with special reference to their geological relations. Am. Assoc. Proc, 

 vol. 27, 1878, pp. 247, 248. 



2 Outline of the geology of Alabama. Berney's Hand-Boo k of Alabama, 1878, p. 140. 



3 (Geological features and divisions of Alabama.) G-eol. Survey of Alabama. Report for 1881 and 

 1882, 1883, pp. 178-181 ; 192-210. 



4 General description of the State of Alabama. Tenth Census U.S., vol. 6. Report on cotton pro- 

 duction in the United States, part 2, 1884, pp. 19-69. 



6 Geological Survey of Alabama. Report on the Cahaba coal field, part II, 1890, pp. 148-150. (Issued 

 January, 1891.) 



G A Historical, Topographical, and Agricultural Survey of the County of Washington. Trans. N. T. 

 State Agric. Soe. for 1819, 1850, p. 865. 



7 The Taconic System, based on observations in New York, Massachusetts, Vermont, and Rhode 

 Island, p. 20, 21 Albany, 1844. 



