482 BULLETIN 10L>, UISTITED STATES NATIONAL MUSEUM. 



sufficiently between tlie paleontological diJtt'erentiations of th<; Ne^^ 

 York and Canadian outcrops to the north and the geological surveys 

 of Booth in Delaware, Ducatel in Maryland, William B. Rogers in 

 Virginia, Emmons in North Carolina, Tuomey in South Carolina, 

 Troost and Safford in Tennessee, D. D. Owen in Kentucky, and other 

 geologists in the Western States and Territories. 



As a reconnoissance it was a brilliant success. The accuracy of 

 its determinations on a large scale have never been impugned. None 

 of its important data have been falsified by subsequent examinations. 

 The mistakes it made were without exception errors of detail, mainly 

 due to the then wild and unsettled condition of large districts of the 

 State and the slight development of its mineral beds, but largely 

 also to the slender fund placed at the disposal of the State geologist 

 annually, vfhich presented him from undertaking tlie necessary in- 

 strumental work for the accurate measurement of sections and loca- 

 tion of lines of outcrop on the map. The geodetic determination of 

 geographical data was impossible. 



This lack of precision, while it did not affect practically the value 

 of the geological knowledge obtained and published provisionally in 

 the annual reports, was destined to be severely felt when the final 

 report came to be written and a geological State map prepared. It 

 gave, as it was sure to give, to the whole final report a general tone 

 of uncertainty respecting the actual thickness of formations and in 

 many cases to the identification of beds and groups of beds at places 

 distant from each other, especially in the coal regions. Had money 

 been at command for instrumental w^ork, many of the great prob- 

 lems in the anthracite region, which have since been settled, would 

 have been settled then, and large sums of money would have been 

 saved to the anthracite industry. The same was true respecting the 

 iron industry. But 50 years ago [i. e. about 1836] the practical im- 

 portance of accurate scientific geological surveys was not appreciated, 

 and the i)eople of Pennsylvania permitted the geological survey of 

 the State to pursue its course under the most onerous disabilities and 

 to stop at precisely the point where its utility was becoming real. At 

 this point the work was resumed in 1874, after an interval of 33 

 years, since which the State survey has simply been a practical con- 

 summation of the earlier preparatory work. 



The lack of precise instrumental work was most severely felt in 

 the preparation of the geological map, for which there was no sound 

 basis whatever and in which every geographical error on Melish's 

 old State map and on the few county maps which existed was neces- 

 sarily either reproduced or modified into some equally objectionable 

 form. So great was the confusion of errors on the maps at the 

 command of the geological survey that an aggregate error in longi- 



