CiKOLOGlCAL AND NATURAL HISTOKY SURVEYS. 451 



9. The great size and miiuber of limestone quarries, exploited for 

 the manufacture of iron, and for fertilizing farms, opened to view 

 every part of the great Siluro-Cariibrian formation, the whole of 

 the Lower Helderburg, all the Devonian and most of the Carbonif- 

 erous limestone beds. 



10. On the other hand, Pennsylvania is singularly destitute of 

 workable veins of the precious metals. Its povert}^ in gold, silver, 

 copper, and lead is extreme. It has but one important zinc deposit 

 and but one nickel mine. In fact, its azoic regions as a whole are 

 barren countiy, containing but a few small magnetic iron ore beds, 

 in strong contrast to the adjoining azoic region of noi'thern New 

 Jersey. What little white marble it possesses makes a sian-ow out- 

 crop foi" a few miles along a single line. Some serpentine rock, a 

 little chrome iron, one lai'ge soapstone quarry, and some kaolin de- 

 posits, conclude the list of its azoic minerals. 



Practically viewed, the geology of Pennsylvania is wholly Paleo- 

 zoic, on the most magnificent scale, with an unexampled wealth of 

 anthracite and bituminous coal, brown heumtite iron ore, limestone, 

 rock oil and I'ock gas: and to the study and description of these its 

 geological survey has from first to last been devoted. 



Little attention has been paid to the lithological study of the 

 building stones of the State, or to their economic desci-iption. The 

 entire State is a roc'c (jiiarry. E^.ery known building stone from the 

 granites, gneisses, quartzites, and traps, to hearthstones, flagstones, 

 brownstone, and limestone can be got with ease, and in infinite 

 abundance on lines of transportation. All the principal outcro]>s 

 of these building stone formations have been located and their places 

 in the Paleozoic series defined in the re])orts, with sufficiently- pre- 

 cise descriptions of their qualities and uses; but beyond this the 

 survey' could not go. 



The paleontolog}' of Pennsylvania was almost oitirely neglected 

 by the survey of 1835-1841, and that of 1851-1854. A considerable 

 collection of fossils was made during the first term, but they were 

 not studied; Avith ihe exception, of the coal plants, resulting in 

 the important re])ort of Leo Lesquereux, embodied in Prof. H. D. 

 Rogers's final report of 1858. The text of this report' was illus- 

 trated by 23 quarto plates of figures. 



The absolutely practical spirit of the Penr^sylvania survey is 

 manifested by the fact that the study of these vegetable forms was 

 prompted by the hope of making them useful as characteristic 

 features of the separate coal beds, enabling the coal men to identify 

 their favorite beds at different collieries and in different basins. 

 This hope proved fallacious; but when the survey M^as resumed in 



1 Goologj' of Pennsylvania, vol. 2, pp. S^rt (o 884. 



