J. Gibson—Salt deposits of Ontario. 363 
and on the south by the county of Lambton. Numerous bor- 
Ings in search of salt have, however, been made in other dis- 
tricts of the Province, but all such attempts have finally proved 
fruitless. Direct experiment, therefore, forces us to the conclu- 
sion that by far the greater volume of salt is to be found under 
the waters of Lake Huron, and this view is partly corrobor- 
ated by the fact that at Port Austin, in Michigan, which lies 
almost due west of the Ontario salt region, there was extracted 
at the depth of 1,198 feet from the surface a brine marking, 
according to Dr. Gcessman, 88° salometer, and containing 17°61 
per cent of sodium chloride. This latter perforation indicates 
at the outset sandstones of the Chemung period; but as the 
depth increases, certainty regarding the exact geological forma- 
tion attained diminishes in like ratio. However, it may with 
some degree of plausibility be conjectured that in this boring, 
as in those in Ontario, the source of the brine is to be found in 
the Salina formation of the Upper Silurian series of rocks. Yet 
it would be altogether unsafe to state unhesitatingly that such 
Teally is the case, seeing that a very great diminution in the 
average volume of the strata overlying the base of the Salina 
formation is unmistakably presented. From the foregoing data 
it is extremely probable that this ancient geographical depres- 
sion or salt-basin had an eastern and western extension of at 
least 85 miles, with probably a much greater stretch from north 
to south. 
Geological features of this Salt area.—The fundamental rocks 
of this district belong, with but one or two exceptions, to the 
Corniferous limestone formation of the Middle Devonian system. 
hese Devonian rocks of Ontario are represented by portions of 
the Oriskany sandstone, Corniferous limestone (including the 
Onondaga limestone), Hamilton, Portage, and Chemung grou 
The following is given as a table showing approximately eke 
geological position of the different formations observed, either 
4s outcrops or by borings in the area in qwestion; and it is 
given in full in order that it may include all the formations 
that present themselves in the numerous borings for salt in the 
Vicinity, and that the relative position of any subdivision may 
at once be recognized :— 
L Middle } ao aia limestone, including the Onondaga lime- 
Devonian, Schoharie grit (not observed in Ontario). 
II. Lower | Cauda-galli grit (not observed in Ontario). 
Devonian, } Oriskany sandstone. 
Lower Helderbe up of Vanuxem, including 
See Leg : only the ee Ta entaculite lim . 
"5 { Onondaga formation, Salina group of Prof. Dana. 
