I70 



NATURE 



\_yunc 23, 1881 



PENNSYLVANIA OIL REGIONS 



THREE years ago tlie Second Geological Survey of 

 Pennsylvania, under the able leadership of Mr. 

 J. P. Lesley, published a report on the oil-well records of 

 the State — a laborious compilation by Mr. J. F. Carll. 

 During the interval the value of this report has been duly 

 tested and acknowledged Ic is a treasury of facts classi- 

 fied and inde.xed for the guidance of the compiler of 

 statistics, the well-sinker, the mining engineer and the 

 geologist, while the general reader may learn much of 

 mterest from its pages. Another report by the same 

 author is just about to appear. It forms a volume of 

 about 500 pages with two indexes, twenty-three plates, 

 and an atlas of twenty-two sheets of maps, well-sections, 

 and working drawings of machinery and tools. We have 

 been favoured with advance-sheets of the Letter of Trans- 

 mission prefixed to the report by iVlr. Lesley, from which 

 we make the followin;^ extracts : — 



" The main featur j of the report is the settlement of 

 the true character of the V^enango oil-sand group as a 

 distinct and separate deposit, with characteristic marks 

 distinguishing it from the Palaeozoic formations of a 

 preceding and a succeeding age ; the differentiation of 

 the group into three principal and other subordinate 

 layers of gravelly sand, holding more or less oil or gas ; 

 the local variability of these sands, their singular per- 

 sistency beneath long and narrow belts of country, their 

 change into barren shales elsewhere, and their indepen- 

 dence of other oil-bearing sands and shales of an earlier 

 and of a later date." 



Some characteristically caustic remarks are made as to 

 the consequences of the contempt entertained by "prac- 

 tical" men for what they consider the '■theoretical" 

 opinions of geologists, and a flagrant e.xample is given of 

 the results of trusting to mere empirical guidance. These 

 passages ought to be well studied by oil-men in Pennsyl- 

 vania and Canada. Mr. Lesley goes on to relate an 

 incident in his own experience. " in 1S41," he says, " I 

 was ordered by the chief of the First Geological Survey 

 to report on the counties lying along the New York State 

 line, and down the eastern bank of the Allegheny River, 

 as far as the Kiskiminitas. Other assistants on that 

 survey had already discovered and reported the geological 

 structure of the Allegheny River and Beaver River water 

 basins, and the rate of descent of the rocks southward 

 and south-westward in relation to tide level had been 

 calculated. My business was to follow and locate upon 

 the map the anticlinal and synclinal rolls which locally 

 change and modify this general dip, and to identify the 

 principal coal beds over a large area. 



"After the discovery of petrol jum (which of course did 

 not in the least set aside or essentially change the struc- 

 ture of Western Pennsylvania as established by the First 

 Survey), I happened to be employed by the Brady's Bend 

 Company to examine their property, and to give them, 

 among other items, an opinion upon the probable exist- 

 ence and depth of oil beneath it. To do this, 1 merely 

 did what any geologist who had thoroughly studied that 

 country would have done ; I calculated the vertical 

 distance from the oil sand on Oil Creek up to coal .A, 

 then I calculated the dip of the measures between Oil 

 Creek and Brady's Bend, and then I identified coal A at 

 Brady's Bend. I reported that the Venango oil sand, // 

 // extended under ground as Jar as Biadys Bend, ought 

 to lie at 1 100 feet beneath water-level. Any geologist 

 who knew the country could have done this. It required 

 no genius, no uncommon knowledge, nothing but a plain, 

 simple, systematic, or scientific, in other words, true 

 theoretical method of applying known facts for discover- 

 ing the unknown. Any oil-man could have done the 

 same if he had noticed the rocky layers as he went up 

 and down the river, and put this and that carefully 

 together. 



"Yet, when after a few months, oil was actually 

 struck at Brady's Bend within a few feet of the depth 

 which I had assigned to it, the astonishment of all classes 

 of oil-men was ludicrously extravagant ; a score or two 

 of copies were made from the manuscript report, and 

 these copies passed from hand to hand as precious things, 

 and their author was looked upon as a prodigy of mental 

 penetration, and was offered large sums of money to 

 locate wells in different districts, none of which offers, of 

 course, were accepted, because he was as ignorant of the 

 aetual existence of an oil-bearing sand in any given 

 locality as everybody else. 



" The story has its moral. Let ' practical ' men believe 

 in and respect the slowly, carefully reached conclusions 

 of ' theoretical ' men enough to take them into consider- 

 ation, so far as to comprehend them, and to govern 

 themselves by them in their own collection and collation 

 of facts relating to their own pecuniary interests." 



Notwithstanding the amount of detailed information 

 now collected regarding the occurrence of the liquid 

 hydrocarbons in these ancient American formations, it 

 must be frankly confessed that we seem to be as far as 

 ever from a clue to their source and history. " The 

 origin of petroleum," says Mr. Lesley, "is still an un- 

 solved problem, and Chapter 26 of this Report merely 

 suggests queries respecting it. That it is in some way 

 connected with Pateozoic sea-weeds, the marks of which 

 are so infinitely abundant in the rocks, and with the 

 infinitude of coralloid sea-animals, the skeletons of which 

 make up a large part of the limestone formations which 

 lie several thousand feet beneath the \'enango oil-sand 

 group, scarcely admits of dispute ; but the exact process 

 of its manufacture, of its transfer, and of its storage in 

 the gravel beds, is utterly unknown. That it ascended 

 rather than descended into them seems indicated by the 

 fact that the lowest sand holds oil when those above do 

 not, and that upper sands hold oil where they extend 

 beyond or overhang the lower. The chemical theory, 

 so-called, which looks upon petroleum as condensed from 

 gas, the gas having been previously distilled from the 

 great black shale formations (Marcellus and Genessee), 

 must face the objection that such a process, if chemically 

 possible, which is doubtful, ought to have distributed the 

 oil everywhere, and permanently blackened and turned 

 into bituminous shales the entire thickness of this part of 

 the earth crust, several thousand feet thick. It fails to 

 explain the petroleum obtainable from the Cannel coals, 

 and from the roof shales of bituminous coal beds. And 

 it fails also to explain the entire absence of petroleum 

 from immense areas of not only shales, but sand and 

 gravel rocks equally underlaid by the Marcellus and 

 Genessee formations." 



One of the most generally interesting questions in the 

 report is one discussed in great detail by Mr. Carll — an 

 episode in the history of the glacial period in North 

 .America. Certain oil-bearing river-gravels are con- 

 nected with a very thick "deposit of Canadian rock 

 fragments not only upon the surface, but to the depth of 

 several hundred feet beneath it in Northern Pennsyl- 

 \ania, a deposit which forms a great belt, more than a 

 thousand miles long, across the continent from Cape Cod 

 in Massachusetts to Iowa and Minnesota beyond the 

 Mississippi River. It was brought from the north by a 

 vast sheet of moving ice which filled the great lakes and 

 rode over the highest mountains to the south of them — 

 bui-ying all New England and New York, Northern New 

 Jersey, Northern Pennsylvania, the Western Reserve in 

 Ohio, and large portions of the States lying further west 

 — projecting long tongues or slowly moving torrents of 

 solid ice southward as far as and even beyond the Ohio 

 River in Kentucky. It drove slowly before it the rein- 

 deer, musk ox, caribou, moose, and other Arctic animals 

 whose bones are found in the diluvial clays of the 

 Kentucky caves ; while the walrus inhabited the shores 



