364 J. Gibson—Salt deposits of Ontario. 
Guelph and Galt formations. 
Niagara formation. 
od “ce 
IV. Mi 
Silurian, 
is*) 
{Anco group. 
edina be 
Of the subdivisions of the Middle Devonian system one is only 
found within the area under review. This is the Corniferous 
limestone formation, which forms by far the greater portion of 
the underlying surface rock. The Lower Devonian is not appar- 
ently represented in these counties, although numerous frag- 
ments of the Oriskany sandstone are scattered here and there 
as angular and lately detached erratics. The rocks of the 
Lower Helderberg group are represented only by the Tentacu- 
lite limestone or so-called water-lime beds. These latter are 
met with in two distinct exposures, each of which presents sim- 
ilar lithological characters. The Onondaga salt group or Salina 
ormation is found to extend under the whole district, so far as 
can be ascertained by borings, forming the foundation rock, so 
to speak, of the water-lime group, and when this is absent, 
immediately underlying the Corniferous and Onondaga lime- 
stones. The Guelph formation—the uppermost subdivision of 
the Middle Silurian series, is only observed by artificial borings 
at the depth of about 1,150 feet from the surface of the ground, 
and underlying the most recent deposits of rock salt. Of the 
Reagen of the Niagara, Clinton, and Medina formations, wé 
ave but very doubtful evidence; and it is only by means of 
specimens of rock brought up by the sand pump, during the 
operation of boring, that we arrive at the probability of their 
existence within the average depth of 1,200 feet from the sur- 
ace. 
Living in the center of this salt region, I have been enabled 
to make frequent visits to the various salt-wells during the ope- 
ration of drilling, to collect the detailed “‘logs” or records of 
1. Kincardine well. 5. Hawley’s well, Goderich. 
2. The Ainleyville well. 6. Clinton well. 
3. Goderich Company's well. 7. Stapleton well. : ; 
4. The Dominion well. 8. Coleman and Gowinlock’s 
: well, Seaforth. 
