DIKES PREVIOUSLY DESCRIBED 261 



posed that they are due to ditch-like excavations made in the shale by running 

 water, which have subsequently been filled with sand by the same agency.'' 



Moore, 1880. In 1880 Mr Charles Moore described a number of fos- 

 siliferous dikes or "veins" intersecting Carboniferous limestones in the 

 Bristol region,* Great Britain. 



Irving, 1883. In his report on the copper-bearing rocks of the Lake 

 Superior region in 1883, R. D. Irving mentions sandstone dikes cutting 

 underlying diabase on the shores of lake Superior. He says if 



"A number of places were noted on the north shore where the overlying sand- 

 stone bed has been removed and large surfaces of the underlying diabase, some- 

 times many hundred feet in length, present the singular appearance of being 

 intersected by veins of sandstone, the seeming veins crossing each other, zigzagging, 

 and branching like true vein-formed material." 



Orton, 1884. In 1884 Edward Orton called attention to " clay veins " 

 in coal, and makes suggestions regarding the manner of their forma- 

 tion.! 



Wall, 1884. In 1884 J. Sutton Wall mentioned and described a num- 

 ber of clay " veins " or dikes in the coal beds of the Monongahela River 

 region of Penns3dvania.§ 



Button, 1889. In his paper on the Charleston earthquake of 1886 || 

 Captain Dutton calls attention to large numbers of craterlets from which 

 quantities of water and sand were discharged during the earthquake. 

 The sand came from beds of quicksand which were near the surface. 



Humphreys, 1886. In 1886 A. N. Humphreys observed and figured a 

 number of clay and slack " veins " or dikes in coal beds in Pennsylvania. 

 They are described as varjnng in thickness from 6 inches to 6 feet. Ac- 

 cording to Mr Hum})hreys, the fissures were " formed partly by tensile and 

 partly by torsional strain upon the seam," and the fissures thus produced 

 "became filled by clay infiltrations from the shales and fragments of 

 sandstone in the overlying strata."^ 



Diller, 1890. The most interesting and important paper on the sub- 

 ject of sandstone dikes is that of Diller,** published in 1890. 



Mr Diller describes a large number of dikes which intersect inclined 

 Cretaceous sandstones and shales about the headwaters of Cottonwood 



* Charles Moore: On abnormal geological deposits in the Bristol district. Quart. Jour, of the 

 Geol. Soc. of London, vol. 37, pp. 67-82. See pp. 7(i, 73-74. 



fEoland D. Irving: The copper-bearing rocks of lake Superior. Monograph V of the U. S. 

 Geol. Survey, pp. 139-140. See aiso pp. 292-293. 



JGeol. Survey of Ohio, vol. v (Economic Geology), p. 143. 



§ Second Geol. Survey of Pennsylvania. Report K 4, pp. 48, 50, 60, 62, 121. 163, 178, 187. 



II Capt. Clarence E. Dutton : The Charleston earthquake of August 31, 1886. Ninth Ann. Rept. 

 U. S. Geol. Survey, pp. 209-5:::8. See pp. 284, 297, 301, 302, etc. 



II Ann. Report of the Geol. Survey of Penna. for 1886, pt. i, pp. 447-451. 



**J. S. Diller: Sandstone dikes. Bull. Geol. Soc. Am., vol. 1, 1890, pp. 411-442. 



