MARYLAND GEOLOGICAL SURVEY 87 



more of the nature of real conglomerates even though the fragments of 

 which they consist are of the same age as the surrounding matrix and 

 are not, as an ordinary conglomerate, composed of foreign rocks. 



Although these curious edgewise structures have been known to geolo- 

 gists for many years, little mention of them has been made in the literature 

 until comparatively recently. The term " edgewise " was coined by 

 Kason in 1901 1 and the occurrence of such structures was mentioned by 

 Bain and Ulrich in 1905. 2 In 1906 Seely described the edgewise con- 

 glomerate in division D of the Beekmantown limestone in the Champlain 

 Valley as the "Wing Conglomerate," naming it after Mr. Wing who 

 made the original observations upon it. 



Seely believed that these flat pebbles could not be laid down in either 

 swift or slow water in the position they are now found and came to the 

 conclusion that they were organic. He described them as three species of 

 the genus Wingia, a new genus of Beekmantown sponges. 



Stose, in 1910, in the Chambersburg-Mercersburg folio of the U. S. 

 Geological Survey, mentioned these conglomerates and ascribed their 

 origin to the breaking up of freshly deposited thin-bedded lime sediment 

 by shallow-water wave action into shingle or flat fragments that were 

 shuffled about on the beach. T. C. Brown, 8 in an article on the origin of 

 certain Paleozoic sediments, reverted to the organic origin of the pebbles, 

 but concluded they resulted from the activities of calcareous algae. He 

 admitted that no specimens preserving any organic structure sufficiently 

 well to prove their origin had been found. Another interesting origin for 

 these conglomerates is that discussed by Grabau in his Principles of 

 Stratigraphy where he explains that they are due to deformation through 

 gliding which has resulted in the complete brecciation of the layers. He 

 distinguishes the intraformational conglomerates in which the fragments 

 lie in all positions, and the edgewise conglomerate where the gliding 

 process has caused the thin cakes to assume a vertical position in the rock 



1 Amer. Jour. Sci., 4th ser., vol. 12, p. 360. 



2 Copper deposits of Missouri, Bull. 267, U. S. Geological Survey, p. 23. 



3 Journal of Geology, vol. xxiii, No. 3, 1913. 



