REPORT OF THE STATE PALEONTOLOGIST 1901 431 



the fossil contents of the series of lenses. Dr Grabau and 

 his assistants have sent in a considerable amount of material 

 which will aid in the solution of the organic feature of the 

 problem. The observations thus far made on these lenticular 

 bodies seem to indicate that they were substantially hardened 

 masses in the sea bottom before the succeeding deposits were 

 laid down over them. It may be said with comparative security, 

 that the faunal content was in considerable measure an impor- 

 tation from the west or southwest. To what degree the sedi- 

 ments were tidal barriers, and the concentration of the fauna 

 in this peculiar form due to the dragging action of tidal currents 

 or accumulation by other mechanical action, and in how 

 far the species represent an actual brief invasion, is yet to be 

 determined. 



Phenomena of like character to those rock masses are found 

 in the " Klintar " which constitute striking headlands on the 

 sea wall of the island of Gothland in the Baltic sea. These are 

 lenticular masses of dolomites without sedimentation structure, 

 lying involved in upper Siluric strata of age equivalent to that 

 of the Clinton and Eochester beds of New York. They have 

 been shown by Wiman 1 to be the product of reef -building organ- 

 isms (corals and bryozoans), though now by wave detrition and 

 by dolomitization but faint trace of such organic structures ap- 

 pears in the rock itself. The Clinton reefs are so impregnated 

 with organisms of form unusual to the contemporaneous de- 

 posits of the western New York province as to raise the ques- 

 tion above referred to concerning the influence of tidal currents 

 in spreading out on these barriers extralimital organisms from 

 adjoining provinces. 2 



1 Ueker silur. Korallenrippe in Gotland. Geol. instit. Upsala. 1897. v. 3. 

 pt 2, p. 311. 



2 Since the above paragraphs were written, the nature of these peculiar 

 rock masses of the Clinton beds has been made the subject of a careful 

 paper prepared by C. J. Sarle (Am. geol. Aug. 1901. p. 282). The author 

 has registered the occurrence of a considerable number of these rock 

 bodies and has brought together much evidence confirmatory of their reef 

 structure. 



