94 
THIRTEENTH REPORT. 
in another 700 feet it lias disappeared. This assuredly indicates one 
of two things: a deep side to the valley — which does not seem to account 
for all the facts in the case; or a gradual change of elevation during 
continuance of the deposit. 
Subsequent to Anderdon time, and in what has hitherto been recog- 
nized as mid-Corniferous, a movement of a different kind has taken 
place. This time it is not tilting, but there appears to have been a 
thrust that reached its maximum along the eastern side of the Anderdon 
deposit — both valley and basin. The evidence is of two kinds: (1) 
^Change of elevation along cross section lines, and (2) a shattered con- 
dition of the eastern edge of the deposit. Every cross section shows 
a gradual slope to westward across the entire width of what must, 
in the order of things, have been a slightly concaved surface at the 
close of Anderdon time. In the Amherstburg quarry basin of the 
Anderdon material this movement is evidenced by relative differences 
of elevation, though the basin surface is still preserved in any but an 
east and west section. 
SINK HOLES. 
The shattered condition of the eastern edge of the Anderdon deposit 
is evidenced by a series of twenty or more sink holes in the land sur- 
face. In localities these are grouped together in numbers. In every 
ease where the rock below has been investigated it has been found 
to be fissured and broken. Along the west side of the deposit the depth 
of stripping impervious to water would in itself explain the absence 
of sink holes. There does not, however, .appear to be the same shat- 
tered condition of the rock, though the core-drill occasionally revealed 
a crack. 
A LINE OF FAULT. 
Associated with this line of sink-holes, and parallel with it, is a 
series of mineral springs highly charged with sulphur, that would seem 
to show a line of fault. This line traverses the old Detroit river chan- 
nel immediately east of the Malden Valley of Anderdon limestone where 
the surface extension is entirely of Silurian dolomite. 
THE MAXIMUM OF THRUST. 
When the depositing of Anderdon sediment ceased, it would seem 
to be evidenced by a maximum depth of overlying Corniferous that the 
lowest elevation within the Anderdon basin — and approximately the 
center of the basin — corresponded closely with No. “8” test hole, at which 
spot there is still the lowest elevation (547.50) of Anderdon within the 
basin. 
And at this precise spot the Corniferous has a higher elevation than 
any other part of the entire surface in question — unless it be between 
No. “8” and No. “9” which, together with it, has felt the maximum of 
thrust. The disturbed elevation of the Corniferous surface of itself proves 
♦Test holes 10 to 13, 2100 feet from east to west, show elevations of Anderdon beds: 571.30, 567.80, 
561.85, and 554.50. „ , 
Test holes 29 and 27, in east to west section, 700 feet, show 574.40 and 563.90. Nos. 15 and 16, 
780 feet east to west, 570.36 and 565.70. Test holes “1,” “9,” *'7,” and 19 and 20 show 574.33, 55S.25, 
538.10, 536.66 and 536.66. 
