SOMETHING ABOUT OIL. 291 



whole thickness of the Hamilton group and the Corniferous 

 limestone, but with nothing more than continued " signs" 

 of oil. The same was done in the salt well at Port Austin, 

 and in the deep boring at Jackson, in the same state. 



In addition to these and other negative evidences that 

 the view of Dr. Hunt is untenable, we have the demonstra- 

 tion of experiment upon the constitution of limestones and 

 black shales. The amount of oil that can be extracted 

 from any sample of the Corniferous limestone is utterly in- 

 significant in comparison with the amount obtainable from 

 the Genesee shale. It is a matter of ocular demonstration 

 that the Genesee shale incloses a vast supply of the mate- 

 rial for petroleum-making, while the Corniferous limestone 

 contains almost none of the material, and comparatively lit- 

 tle of the generated product. I shall insist, then, with my 

 distinguished friend Dr. Newberry, late President of the 

 American Association for the Advancement of Science, upon 

 the correctness of that view which regards the black shales 

 as the chief generators of supplies of native petroleum. I 

 dissent from the position of Dr. Hunt with the utmost defer- 

 ence to the weight of his authority, and only because I have 

 enjoyed opportunities seldom equaled to examine the geol- 

 ogy of all the " oil-regions" east of the Rocky Mountains. 



The petroligenous formation may be present in the ab- 

 sence of reservoirs for the reception of the product. There 

 is a well-defined belt along the eastern and the western 

 slopes of the lower peninsula of Michigan which is imme- 

 diately underlaid by the Genesee shale, capped by a de- 

 posit of argillaceous surface materials adequate to prevent 

 wastage; but no oil has accumulated, because no space has 

 been provided for it. In some portions of the Enniskillen 

 region, twenty miles distant, the geological conditions are 

 perfectly identical, except that a bed of gravel lies at the 

 bottom of the drift materials, and immediately upon the 



