Clinton and Niagara Strata. — Sarle. 285 
the position of many of the fossils, he considered these bodies 
accumulations of organisms swept together by eddies and cur- 
rents charged with the fine sedimentary matter in which we 
now find them. Dr. Ringueberg listed forty-eight species. 
Prof. J. M. Clark under the announcement "Faunal Col- 
onies in the Clinton beds,"* mentions the occurrence of these 
bodies in western New York through Orleans and Niagara 
counties. He describes them as lenticular masses of limestone 
ten to thirty feet in diameter and entirely disconnected, those 
in one plane lying imbedded in the midst of the Clinton lime- 
stone, though of wholly different texture and composition 
therefrom ; in another, lying in the shale above the limestone 
and displacing or being surrounded by the lower shaly beds of 
the Niagara group (Rochester shales). 
Amadeus W. Grabau, in his "Paleontology and Geology of 
Niagara Falls and Vicinity," f under the heading "Limestone 
Lenses of the Clinton" says : "Ai intervals in the upper Clin- 
ton limestone may be seen large lenticular masses of compact, 
hard, apparently structureless limestone, often concretionary 
and not infrequently showing numerous smooth and striated 
surfaces of the type known as 'slickensides' and which are in- 
dicative of shearing movements." 
He mentions the lenses in the Rome, Watertown and Og- 
densburg railway cut under Lewiston heights, as entirely im- 
bedded in the limestone from which they are differentiated by 
their structureless character. He also notes the mass seen in 
the New York Central railway cut on the side of the gorge 
near the third watchman's hut (see Fig. 6.) as lying between 
the upper limestone and the overlying shale, partially im- 
bedded in both. He finds those vnder Lewiston bights rich in 
orthoceratites and shields of trilobites ; and those of the gorge 
yielding chiefly brachiopods. From these lenses he lists 
twenty-eight species. Dr. Grabau observes that the origin of 
these lenses is still obscure. 
THEORIES OF ORIGIN OF THE LENSES. 
By Mechanical Agency: The presence of currents which 
would enmass such quantities of organic material in compar- 
atively small spaces should have left other conspicuous struct- 
* Report of the state Pa/eon to/o^/st for 1 S99 (pub. 1900). 
^Bulletin, N. Y. State Museam, No. 45, vol. ix, April, 1901, pp. 99-102. 
