266 f. F. XEWSOM CLASTIC DIKES 



dered by complementar}^ faults have settled down relativel}" to tlie bor- 

 dering masses" and have carried the overlying sands down w4th them- 



Gresley, 1897. In 1897 W. S. Gresley described and figured a number 

 of clay " veins " or dikes in the Pennsylvania coal beds and elsewhere.^ 



Whitten, 1897. In the Proceedings of the Indiana Academy of Science 

 for 1897, pp. 234-240, W. W. Whitten describes pockets of sand in clays 

 and dikes of clay in sand in glacial deposits at South Bend, Ind. Some 

 of the dikes extend downward from 4 to 8 feet into underlying sands. 



White, 1898. In a paper on the Origin of Grahamite, in 1898 Professor 

 I. C. W^hite mentions the Ritchie county, West Virginia, vein, and con- 

 cludes that its material came mostly from oil sands which lie 1,530 feet 

 below. t The deposit is two-thirds of a mile long, and varies in tliick- 

 ness from a few inches to 4 or 5 feet. 



Grabau, 1900. In 1900 A, \V. Grabau described a sandstone dike in 

 the Bullhead limestone in Erie count}^ New York.:|: The dike is 

 squarely cut off at the top, where the Onondaga limestone rests on its 

 truncated end. Its width is about 2 feet, and it sends off numerous 

 branches into the limestones that inclose it. The branches are very 

 irregular, and sometimes appear as much as 30 feet from the main dike, 

 from which they are apparently isolated. Grabau thinks that the forma- 

 tion of the fissure and " more or less violent injection of the sand " 

 from above occurred simultaneously. 



Greenl}^ 1900. In 1900 Edward Greenly described a number of pipes 

 or plugs of sandstone that penetrate limestones on the east coast of 

 Anglesey, Wales. § 



Ransome, 1900. In volume xxxof the Transactions of the American 

 Institute of Mining Engineers, || F. L. Ransome describes a dike of shale 

 fragments, pebbles, and other material which cuts horizontal sandstones 

 near Oura}^ Colorado. Regarding its origin he says : 



"A fissure was formed, accompanied by some faulting, and was filled, chiefly 

 from above, by fragments of fissile black shale, which does not occur in the strati- 

 graphically lower beds exposed in the immediate vicinity, and partly by material 

 from the lower light-colored beds, forming the present wall. Tiie fragments from 

 both sources were well mixed together, and probably formed a stiff" mud crowded 

 with fragments of shale." 



The dike is known to extend to a depth of 730 feet. 



* W. S. Gresley : Clay-veins vertically intersecting Coal Measures. Bull. Geol. Soc. Am., vol. 9, 

 pp. 35-58. 



fl. C. White : Origin of Grahamite. Bull. Geol. Soc. Am., vol. 10, 1898, pp. 277-284. 



X Bull. Geol. Soc. Am., vol. 11, 1899-1900, pp. 357-361. 



g Edward Greenly : On sandstone pipes in the Carboniferous limestone at Dwlban point. East 

 Anglesey. The Geological Magazine, new series, decade iv, vol. vii, pp. 20-24. 



Edward Greenly : On deflected glacial striie at Dwlban point, East Anglesey. Ibid., pp. 24-25. 



II F. L. Ransome : A peculiar clastic dike near Ouray, Colorado, and its associated deposit of 

 silver ore. Trans. Amer. Inst, of Min. Engs., vol. xxx, 1900, pp. 227-236. 



