214 S. G. Williams — Gypsum Deposits in New York. 



thickness of about 25 feet, to its proper place in the section, 

 especially since the space of nearly a quarter of a mile between 

 the fossil-bearing beds on the lake shore and the gypsum quar- 

 ries, is concealed by drift. Fortunately the valley of a brook, 

 separated only by a single field from the nearest quarry at this 

 point, affords a continuous line of outcrop from the fossiliferous 

 limestones on the lake to the top of No. 2, by which its con- 

 tinuity is assured. The top of No. 2 is 20 feet above the lake- 

 level, which is- also the height of the floor of the nearest plaster 

 quarry. Add to this the fact that the character of No. 2 

 corresponds with that of the bed of tough blue limestone which 

 forms the bottom of all the southern quarries, and there is no 

 reason to doubt that the plaster series belongs in the covered 

 space between Nos. 2 and 4, widened probably by the local 

 easterly dip mentioned above, — a position to which, in the 

 absence of any local irregularities, it would be unhesitatingly 

 assigned by any geologist. 



There is then no doubt that the gypsum deposits here form 

 a part of the fossiliferous series, lying above beds containing 

 Eurypterus, Leperditia alta, Nucleosinra ventricosa and Meris- 

 tella bisulcata, and below, or in close connection with, beds con- 

 taining well-marked fossils of the Pentamerus and Shaly Lime- 

 stone horizons of the Lower Helderberg. It should also be 

 borne in mind that, apart from the gypsum beds, the entire sec- 

 tion from the lake level to the Oriskany sandstone, is made up 

 of drab limestones with frequent blue seams, sometimes of con- 

 siderable thickness, as in No. 5. Some of these limestones, both 

 at the bottom and top of the series, are highly laminated, show- 

 ing thin layers of slightly different colors, and nearly all hold 

 a considerable amount of impurities. A test which was made 

 of No. 1 showed 25|- per cent of insoluble matter, so fine as 

 to cause difficulty in filtering; while some of the higher beds 

 above No. 5 are said to have been burned for hydraulic lime at 

 an early day, yielding a cement of good quality, thus showing 

 that they are probably no purer than No. 1. There is indeed, 

 even if we set aside the fossil evidence now gained as to geologi- 

 cal age, no such lithological change in the limestones as to 

 warrant the reference of the lower portion of them to the 

 Salina Period, and the upper part to the Lower Helderberg. 

 Nor is it likely that any such reference would ever have been 

 made had it not been for the presence of the gypsum deposits. 

 These deposits in the regions both east and west of Cayuga 

 county appear, from the state reports, to occupy a pretty definite 

 place in strata bearing intimate relations with the shales of the 

 salt group ; to occur in irregular masses enclosed in marly 

 shales whose lamination they sometimes share and sometimes 

 disturb ; and to be divided often into two ''ranges" by a pecu- 



