NIAGARAN MARINE INTERVAL 471 



beds of the Lockport or the top of the Kochester, a creeping and inter- 

 stitial rearrangement of the fine calcilutytes, with accompanying defor- 

 mation which looks like a complicated series of foldings. This is a 

 structure long familiar to German geologists under the name "Gekrose," 

 for which I have substituted the term enterolitliic structure. 73 It is a 

 phenomenon accompanying the diagenetic alteration of certain fine cal- 

 careous rocks and is in no case of tectonic origin. A similar structure is 

 seen in the otherwise horizontally bedded salt deposits of the New York 

 Salina and in numerous deposits in various parts of the world. Its oc- 

 currence might easily lead one not familiar with such tilings to think of 

 a tectonic deformation of the beds, and in some cases in the Niagara 

 Gorge it suggests superficially an unconformity and hiatus. Such does 

 not, however, exist, and the differences in faunal character found in the 

 Niagaran beds of the different parts of the country must be accounted 

 for by the variation of the factors influencing the distribution of organ- 

 isms. Nor does such difference of faunal character in closely adjoining 

 districts necessarily imply actual land barriers, for we have abundant 

 evidence today of different faunas in closely adjoining districts of the 

 same ocean. One might cite the fauna of Gasco Bay and of Massachu- 

 setts Bay and again compare the latter with the faunas of Vineyard 

 Sound. This disregard of other than continental barriers deprives Schu- 

 chert's work in paleogeography of much of its value, for his successive 

 paleogeographic maps are chiefly based on the principle of land barriers 

 for faunal separation. 



It is highly improbable that during deposition of the marine Nmgaran 

 any direct connection existed with the Atlantic in the Appalachian re- 

 gion. Not only was the Appalachian old land the source of the clastic 

 sediments, but the materials here are coarse and in many cases merge 

 into continental sediments. Indeed in most cases along the Appalachians 

 the Niagaran beds (Eockwood) are largely the eroded and reworked con- 

 tinental elastics of early Siluric and late Ordovicic time which preceded 

 them. Schuchert's maps, which show connections with the Atlantic in 

 the New York City region during Clinton and Rochester time, are most 

 certainly at fault. These maps may be further criticized in thai they 

 show Niagaran formation distributed over too limited an area. They 

 leave out of consideration the fact that an enormous amounl of erosion 

 lias occurred during Salina time and also during Monroe time, Hie evi- 

 dence for which will be given presently. It is difficull to understand 



73 See F. Felix ITahn : Neues Jahrbuch fiir Mlneralogle, etc. Bellage Band \\wi. pp. 

 \\A-'.M, pi. ill, fig. 2; also text figure 15. See also Principles of Stratigraphy, chapter w. 



