554 HISTORICAL GEOLOGY. 



that attracted attention was made when boring for gas or oil, in 1878, in 

 Wyoming County, a dozen years after the discovery at Goderich, and ten 

 years before that near Cleveland, Ohio. 



By evidence from borings, rock salt is now known to occur in New York 

 at depths of 800 to 3000 feet or more, over an area measuring 150 miles 

 from east to west, and 60 to 65 miles in width if extending only to the 

 Pennsylvania boundary. The northern limit of the area is near Morrisville, 

 where 12 feet of salt were found, and near Leroy, 100 miles west of 

 Syracuse, where a bed 40 feet thick exists. To the south, in Livingston 

 and Wyoming counties, beds of salt occur at depths of 1000 to 2500 feet, 

 and they have an aggregate thickness of 50 to 100 feet, some beds of pure 

 salt being 40 to 80 feet thick. At Ithaca, the several beds of salt have 

 together a thickness of 250 feet ; they alternate with shale between depths 

 of 1900 feet and 3130 feet. At Goderich, six beds 6 to 35 feet thick were 

 passed in a boring 1617 feet deep ; and other localities occur within 40 miles 

 to the north, east, and south. Near Cleveland (at Newburg) there are four 

 beds 5 to 50 feet thick in a range of beds 500 feet thick, betAveen 2000 and 

 2500 feet below the surface. The evidence shows that the Goderich basin 

 is independent of the New York, as pointed out in 1876 by T. S. Hunt. 

 How it is related to the Cleveland basin is not positively known. 



The strata are non-fossiliferous ; but as they include beds of limestone, 

 this is probably owing to loss of shells and other relics by trituration through 

 the gentle movements of the water. The beds abound in mud-cracks, and 

 other evidences that they were made as mud-flats or bottoms in shallow 

 water. The facts are believed to prove that the region through which the 

 salt beds extend was an area of great salt marshes or flats, or in other words 

 " salt-pans," over which sea water, admitted at intervals from the interior 

 continental sea, evaporated and deposited salt. The fineness of the material 

 of the shales is such as would be produced by the gentle ripplings of such 

 waters. 



The gypsum in the beds sometimes constitutes layers, but oftener parts 

 of layers, or imbedded masses, as illustrated in the following figures (from 

 Hall); but the most of the gypsum is connected with the overlying Water- 

 lime beds. The lines of stratification in the beds sometimes run through 

 the gypsum, as in Fig. 792 ; and in other cases the layers of the shale are 

 bulged up around the nodular masses (Fig. 793). In all such cases, the 

 gypsum was formed after the beds were deposited, by the action of sulphuric 

 acid on an imbedded mass or bed of limestone, converting CaOgC into gyp- 

 sum (hydrous lime sulphate = Ca04S + 2 HjO). It may be now forming. 

 Sulphur springs, emitting sulphuretted hydrogen, are common in New York, 

 and especially about Salina and Syracuse. Dr. Beck describes several, and 

 mentions one, near Manlius, which is " a natural sulphur bath, a mile and a 

 half long, half a mile wide, and 168 feet deep, — a fact exhibiting in a strik- 

 ing manner the extent and power of the agency concerned in the evolution 

 of the gas," and showing, it may be added, that the effects on the rocks 



