THE STRUCTURAL CLASSIFICATIOK 577 



associations of oil, sulphur, sulphuretted hydrogen, gas, gypsum, dolomite, and 

 salt, constituting collectively what might be termed the oil-phenomena repre- 

 senting a group of secondary products as distinguished from the mother-strata 

 or sediments out of which they have been produced. Moreover, so far as I am 

 aware, he first pointed out the existence of anticlinal hills in the Coast Prairie 

 and their connection with the oil-phenomena. . . . Captain Lucas early 

 noted that sulphuretted hydrogen escaping from the earth under certain condi- 

 tions deposited sulphur in crevices near the surface. Such phenomena he ob- 

 served at Spindle Top before commencing his well. At High Island, Galveston 

 County, Texas, work was temporarily suspended on a well hole and the orifice 

 stopped with hay in order to prevent obstructions from debris. Afterward 

 when the plug was withdrawn the hay was found to be imbedded in a matrix 

 of sulphur, undoubtedly deposited by the escaping gas. ... No topographic 

 surveys have ever been made of any portion of the Coastal Prairie, and hence 

 the slight irregularities of its contour are discernible only with difficulty. 

 Until Captain Lucas's investigations, certain low elevations which have since 

 become the most important features of the landscape were hardly noticed. I 

 allude to low swells or hills, such as Spindle Top, which occur here and there 

 and now attract attention from their supposed relation to the occurrence of 

 oil beneath them. ... In the generally monotonous monoclinal structure 

 there are a few wrinkles or small swells likely to escape the eye of even the 

 trained observer, and yet of a character which may have an important bearing 

 on the oil problem. These are the circular or oval mounds already described 

 which were first recognized by Captain Lucas. When he pointed out Spindle 

 Top hill to me, my eye could hardly detect it, for it rises by gradual slope only 

 ten feet above the surrounding prairie plains. I was still more incredulous 

 when he insisted that this mound, only 200 acres in extent, was an uplifted 

 dome. But Captain Lucas said that I would be convinced of the uplift if I 

 could see Damon's mound in Brazoria County. In August, 1901, I visited that 

 place and then returned for a second look at Spindle Top and was convinced 

 that if these hills are not recent quaquaversal uplifts no other known hy- 

 pothesis will explain them." 



Quoting from Lucas at a later date :*^ 



"At Jefferson Island pure rock-salt was penetrated to a depth of twenty-one 

 himdred (2,100) feet without finding bottom, and at Belle Isle rock-salt, hav- 

 ing a depth of twenty-seven hundred and forty (2,740) feet (pierced in 1907), 

 was discovered with parafflne oil and large lenses of pure sulphur. 



"The successful results attained by his explorations in Louisiana led the 

 writer to extend the study of a nascent 'dome theory' into Texas and to apply 

 it to the various phenomena occurring on Spindle Top, a low elevation of only 

 ten to twelve feet above the surrounding prairie, and to drill finally on this 

 dome against the advice of his friends, with the well known result that the 

 largest well ever discovered in the United States and variously estimated at 

 from 75,000 to 100,000 barrels per day had its birth on the tenth day of Jan- 

 uary, 1901. 



« Science, n. s., vol. 35, no. 912, June 21, 1912, pp. 962-963. 



