260 J. F. XEWSOM — CLASTIC DIKES 



the surface, and in others to cause only slight overflow. As the water 

 sank back into the fissures an inverted cone structure was formed in 

 some cases. 



Fontaine, 1873. In 1873 Professor Wm. M. Fontaine described the 

 Grahamite deposit in Ritchie county, West Virginia.* 



AVurtz, 1869. In 1869 Mr Henry Wurtz described f the Ritchie county 

 Grahamite vein, which intersects Carboniferous sandstones and shales 

 in West Virginia. He reaches the conclusion that the material in it 

 came from underlying strata intersected by the fissure in which the 

 deposit occurs. 



A dike of Grahamite in Colorado is also mentioned by Mr Wurtz. 



Milne, 1874. In 1874 John Milne described a schistose dike which 

 intersects black slates on Facheux ba}', Newfoundland. J 



The dike described is 3 feet 6 inches wide at the top and 2 feet 3 inches 

 wide at the bottom ; it contains carbonaceous matter. Other similar 

 dikes are mentioned as occurring in the district. 



Stevenson, 1875. In 1875 J. J. Stevenson mentioned and described 

 a number of clay dikes occurring in the coal beds of western Pennsyl- 

 vania. § Clay dikes or " veins '' coming from both above and below are 

 mentioned on page 276. On pape 279 of Report K a case is mentioned 

 where the coal for 2* feet at each side of a 6-inch intrusion "is thrown 

 up sharply and without any snapping at the angles, but the upturned 

 portion is badly shattered." On page 316 a 7-foot clay intrusion is 

 mentioned. 



White, 1875. In 1875 I. C. White mentioned '* cla}- veins " occurring 

 in the bituminous coal region of western Penns3dvania.ll 



Kimball, 1876. In 1876 J. P. Kimball described a deposit of Gra- 

 hamite, which has been intruded from below, in Mexico.*[ This deposit 

 intersects shales at a low anticlinal fold, and at the contact of the shales 

 with overlying conglomerates and sandstones spreads out into a lentic- 

 ular mass. 



Richardson, 1877. In his report on the coal fields of Nanimo and 

 Comax "^ calls attention to sandstone dikes in shale and remarks : 



"One of the so-called dikes is quite vertical, seven feet thick, and strikes north 

 73 degrees east. From the character of the walls of some of these dikes it is sup- 



* Am. Jour. Sci. and Arts, 3d series, vol. vi, pp. 409-416. 



t On the Grahamite of West Virginia and the New Colorado Resiuoid. Pioc. Amer. Assoc. Adv. 

 Sci., vol. xviii, pp. 124-135. 



I Quart. Jour, of the Geol. See. of London, vol. xxx, p. 731. 



g See. Geol. Survey of Pennsylvania, 1875, Report K, pp. 53, 228, 27G, 279, 306, 307, 308, 316, 324, 326. 

 Also Report K K K, pp. 295-301, and Report K K, pi. 876. 



|! Sec. Geol. Survey of Pennsylvania, Report Q, pp. 74, 78. 



*^ James P. Kimball: On the occurrence of Grahamite in tlie Huasteca, Mexico, etc. The .\mer. 

 Jour. Sci., 3d series, vol. xii, 1870, pp. 277-280. 



** Report of Progress for 1870-1877 ot the Geol. Survey of Canada, p. ISO. 



