

176 Acid Springs and Gypsum of the Onondaga Salt Group. 

 ident from an analysis made in April, 1846, by Prof. Croft of 



King's College, Toronto, which is confirmed by a partial exami- 



nation by myself, of a specimen of water brought from the spring 

 in June, 1845. 



The specific gravity of the water was much lower, and the 

 amount of foreign ingredients much less, than in that collected by 

 myself, but the proportion of bases to the acid was much greater. 

 The proportion of the lime to the acid I found to be about 1: 15, 

 and that of the magnesia 1:90, while Prof. Croft's determination 

 gave about 1 : 6 and one to 1 : 15, respectively. That collected in 

 1845 is a nearly saturated solution of gypsum, while that of 1847 

 contains no more than about 7 parts in 10,000. 



These facts indicate a rapid change in the constitution of the 

 spring, and its situation shows it to be of comparatively recent ori- 

 gin ; for although the powerful acid has destroyed all traces of veg- 

 etation for a distance of several yards around the source, the 

 water issues from beneath the roots of an enormous pine-tree, 

 whose half decayed stump still stands several feet in height, 

 while the crumbling mould from its slow decay, forms the surface 

 soil for some distance around. Without overlooking the antisep- 

 tic virtues of the mineral substances contained in this remarkable 

 spring, this fact shows that its antiquity can scarcely be greater 

 than a century, if indeed half that cycle may not extend beyond 

 the time of its first development, while the rapid decrease in the 

 quantity of the saline bases shows that its character remains con- 

 stant scarcely for a twelve-month. It should have been observed 

 that there are four or five basins within the distance of as many 

 yards, and that they are situated on the summit of a low mound 

 which rises with a gradual slope from the marshy plain. 



The probable cause of these changes will be seen by adverting 

 to the character of the gypsum deposits of this formation, which 

 I regard as having an intimate connection with this class of springs. 

 The investigations of Mr. Hall, in New York, and Mr. Murray, 

 in Canada, unite in showing that the gypsum of these rocks al- 

 ways occurs in hillocks or dome-shaped masses, varying in size 

 from one foot to 300 or 400 feet in diameter, and always near 

 the surface of the formation. Sections of these masses show 

 them resting upon undisturbed strata of limestone, while the su- 

 perior strata are thrown up and rest upon the flanks of the intru- 

 ded hillock, often very much broken, and, as Mr. Hall has remark- 

 ed, in part consumed, so that one is at a loss to account for the 

 disappearance of a large portion of the overlying strata. In one 

 case observed by Mr. Murray, a slender cylinder of gypsum passes 

 through several beds of the limestone, and at last terminates in a 

 cone of the usual form, which is entirely superior to the lime- 

 stone formation and surrounded by the tertiary clay of the region- 

 The comparatively recent origin which this assigns to the gypsum 



