Identifier: annualreport191002onta (find matches)
Title: Annual report
Year: 1891 (1890s)
Authors: Ontario. Dept. of Mines
Subjects: Mines and mineral resources
Publisher: Toronto
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: University of Toronto

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howing the present land surface must, of course,be moved upwards a distance equal to the vertical throw. If this point is not consideredwhen studying the cross-section one might, at first glance, get the erroneous impressionthat a normal fault had occurred, carrying down the east side of the lake, but theunbroken and continuous position of the diabase sill and floor of the Cobalt con-glomerate will show that this is not the case. Section Y, Z, plate V The cross-section shows the great fault at La Rose mine as it has been worked outat and near the main shaft. It is a reverse fault, with a steep south-easterly dip at thesurface which becomes less on the lower levels. There is a vertical displacement of210 or 220 feet, but the extent of the horizontal movement has not been ascertained. On the first level, 45 feet south of the main shaft, a drift runs west under therailway to the boundary of the property. The fault is encountered at a distance of 1913 Cobalt-Nickel Arsenides and Silver 95
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8 M (II) 96 Bureau of Mines No. 4 55 feet in this drift, and is well defined, because the Nipissing diabase sill has beencarried down and a small uneroded patch now lies against the Cobalt series of sedi-ments. The roof of the drift for 25 feet west of the fault, and the floor for 10 feetwest, is diabase. On the surface the diabase outcrops west of the railway tracks,opposite La Rose main shaft. On the second level the fault occurs 43 feet immediately west of the main shaftin a drift where coarse boulder conglomerate has been faulted down against fine-grained greywacke. The contact of the Cobalt series and the Keewatin greenstonesoccurs on this level at the main shaft. On the third level the fault is found 12 feet east of the centre of the main shaft,and it may also be seen in the shaft itself at the top of the first ladder above thislevel. At these points the fault line is well shown, because the conglomerate andgreywacke abut against the Keewatin greenstones. In the winze at the thi

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