380 O. E. LE ROY — GEOLOGY OF RIGAUD MOUNTAIN, CANADA 



it is impossible to state the exact number, though it is probably in the 

 neighborhood of 25. The garden gradually rises toward the south- 

 west; the difference in level between the lowest and highest ridge is 

 about 125 feet, the former being 350 feet above sealevel. Practically all 

 the boulders are the debris of the mountain in the immediate vicinity, 

 not more than ] per cent being Paleozoic and Laurentian erratics. The 

 spaces between the boulders are quite empt}'^, and in the northeast part, 

 where the deposit is deepest, several excavations have been made, one 

 of which was continued to the depth of about 20 feet without reaching 

 bed rock or any accumulation of soil in the interspaces. It is probable, 

 however, that the dee})est parts do not much exceed 25 feet, as part of 

 the country south is drained under the garden, in wet seasons the trick- 

 ling of the water being distinctly heard, while on the occasion of one 

 visit running water was noted in the 20-foot hole. 



Separated b}' but a short distance ("rotn the above is the second de- 

 posit, which, commencing just below and north of the peak, fills in the 

 triangular area between the porphyry and syenite. The ridges are at 

 first irregular and are composed of very large and slightly rounded 

 boulders, but gradually they broaden out and develop into a series as 

 regular and better marked than those of the Devils garden. The}' run 

 in a southwest direction — tliat is, at riglit angles to the trend of the 

 ridges of the former deposit. The other characteristics are the same as 

 in the case of the Devils garden, with the exception that this deposit is 

 probably not so deep. 



The character of the boulders in the Devils garden is such as to show 

 that they came from the mountain immediately to the east, while those 

 composing the second deposit were derived from the cliffs below the 

 peak. With reference to the origin, it was thought both deposits were 

 formed by the action of the waves during the post-(ilacial submergence, 

 and that, owing to a comparatively rapid rise of the land and the ex- 

 posed position the mountain would then occupy, the finer detritus was 

 washed out and deposited in the gravel and sand terraces which now 

 flank the mountain in this vicinity. If that were the origin, then the 

 Devils garden would have the character of a pocket beach and the second 

 deposit that of a spit. The objection that has been made to the above 

 is that no beaches now in process of formation show the above charac- 

 teristics, there always being some packing of the finer detritus between 

 the boulders. It has therefore been suggested that during the Glacial 

 period, when the ice-sheet impinged against the projecting and prom- 

 inent parts of the mountains, lines of drainage were developed owing 

 to the obstructions encountered, and that the courses of these glacial 

 streams were through the depressions, one to the east and the other to 



