Report of the State Geologist. 159 



The collections made at the Livonia salt shaft by Mr. D. D. 

 Luther show very clearly the extension of the Lower Helderberg 

 fauna to that longitude, but thus far no fossils of that age have been 

 found in the material of that horizon brought out from the salt 

 shafts on the west side of the Genesee Iwiver. As the natural 

 result of the intermingling of an increased proportion of the 

 argillo-magnesian sediments of the Waterlime epoch with the 

 nearly pure calcareous sediments constituting the fossiliferous 

 Lower Helderberg group the ocean waters became unfit for the 

 support of those forms of life which so abundantly characterize 

 the different members of that group in its more easterly exposures. 

 It is no doubt true that the sediments of that age do extend 

 farther to the westward, but their individuality is lost, the 

 impure magnesian sediment prevailing over the calcareous material 

 of eastern origin, the whole mass becoming of a dirty gray color 

 and quite unfit for the support of life in any kind of organism 

 except perhaps a few seaweeds, or other obscure organic 

 manifestations. 



It is in only those parts of the Waterlime group = Rosendale 

 limestone, where these turbid sediments are not deposited, 

 that the characteristicts fauna of that horizon, the Eurypteridae, 

 flourish, and fossils of this kind are extremely rare, or altogether 

 wanting in the central portion of the State. 



The maps, sections and reports of myself and Mr. Darton, 

 assistant geologist, which were originally communicated with 

 this report have been withdrawn since they could not be engraved 

 in time for publication. These will be incorporated with the work 

 of 1893, and be published with the work of the same year. 



The report on the Livonia salt shaft, so far as the work had 

 progressed, was also communicated with the present report, but 

 the delay in printing has given time for completing the work 

 upon the shaft and the later observations will be combined with 

 the earlier, making a single report upon the results obtained dur- 

 ing the two years of observation, and the collection of material 

 from th^ several geological formations passed through in the 

 progress of the work. This paper, witii its maps, sections of salt 

 wells, etc., will be communicated with the report of the State 

 Geologist for 1893. 



