4 ENVIRONMENT OF VERTEBRATE LIFE, ETC. 



the pebbles and bowlders forming at the base of the cliffs on the Gaspe 

 Peninsula, where an unbroken series of rocks represents several geological 

 periods.^ 



In cases of marine planation, where the waves have advanced for a 

 long distance either over reduced cliffs or across a country of originally 

 more subdued topography, similar conglomerate would result, but the 

 debris would probably be of smaller size, due to prolonged wave-action, 

 and would be thoroughly mixed and spread over a far larger area, and recog- 

 nizable fossils of a contemporaneous fauna would be present. 



If the waters should advance over a large area where the rocks are 

 inclined, even at a low angle, and successive outcrops occur in parallel 

 bands, a mixing of the rock debris and older fauna would result from the 

 sequent erosion of the successively outcropping beds. We might expect 

 such a basal conglomerate to have been formed by the encroaching Coman- 

 chean Sea in Texas or more strikingly as it conquered the southern part of 

 the Arbuckle uplift. If the encroaching strand were parallel to the strike 

 of the outcrop, the various elements would be distributed in broad bands 

 unless disturbed by currents. If the advancing strand were at right angles 

 or any large angle to the strike of the outcrop, the mixing of the material 

 and older faun^ would be far more complete. 



In the case of marine planation of a land of low relief, it would be 

 expected that much of the material of the conglomerate would be fragments 

 of loosened material which had lain long upon the surface or buried in the 

 residual soil, and the bowlders would present a far more weathered appear- 

 ance than if the waves had cut back a cliff of hard rock. 



In the case of marine waters breaking in upon a land of low elevation, 

 as the relatively rapid flooding of a peneplain or the submergence of a land 

 below the sea-level by the failure of barriers, the advance of the strand 

 would be so rapid that little effect would be produced upon any residual 

 masses of hard rock and there would be no evidence of sea cliffs, shelves, etc., 

 except at the highest level of the water, and little or no fresh material 

 would occur in the conglomerate, but a large amount of weathered material 

 might be expected. The loosened regolith of the invaded land would be 

 sorted and the conglomerate would alternate with irregular beds of finer 

 material where quieter water or greater depths permitted its accumulation. 

 One would not be surprised to find in such deposits the remains of land 

 plants and animals. Noble, in his account of the history of the Grand 

 Canyon of the Colorado, cites one such instance. 



' Clark, J. M., New York State Museum Memoir No. 9, 1908. 

 2 Folio 98, Tishomingo, U. S. Geological Survey. 



' Noble, L. P., The Shinumo Quadrangle, Bull. 549. U. S. Geological Survey, pp. 42 and 

 80-83, 1914- 



