264 EDWARD M. BURWASH 



more largely composed of fragmental materials than the western 

 one, which is essentially a lava-cone. The older cone contains much 

 material derived from the underlying rocks, especially fragments of 

 granite and the columnar Miocene andesite which exhibit evidences 

 of the high temperature to which they have been exposed within the 

 vent. In the case of the granite the result is a general softening 

 and tendency to disintegration, while the andesite blocks show 

 cooling cracks which extend some distance from their surfaces 

 inward. 



That there was a still earlier cone which has been destroyed is 

 proved by the remnant of a large lava-stream on the nothern side of 

 the older remaining cone, the upper part of which has been cut off 

 so that it presents a precipitous face, inside of which the older of 

 the present cones has been built up. The cones as they now stand 

 are therefore later than that from which this lava was extruded. 

 The lower part of this old flow descended into the valley of Stony 

 Creek, now occupied by Garibaldi Lake, but has been eroded away, 

 probably by the glacier which occupied the valley during the 

 second period of glaciation. This would indicate that the period 

 of activity of this volcano extended back into the later of the two 

 glacial epochs. 



There is, on the other hand, abundant evidence that vulcanism 

 continued for some time after the ice had retreated nearly to its 

 present limits. Lava-flows from the western crater of Red Moun- 

 tain have filled Stony Creek valley for a distance of about a mile 

 and a half, and their surfaces are entirely unglaciated. The 

 resultant damming of the creek has produced Garibaldi Lake, 

 whose waters now find their outlet along a channel between the 

 edge of the lava-flow and the northern wall of the valley until they 

 reach a recess in the lava which forms the basin of Lesser Garibaldi 

 Lake. From this point onward the stream follows a subterranean 

 channel under the lava flow, beneath which it reappears at the foot 

 of the cliff known as "the Barrier," which has been formed by the 

 undercutting of the lower end of the lava-flow. At times of 

 exceptionally high water, a part of the stream flows over the surface 

 to Stony Lake, and thence over the Barrier into the lower valley. 

 The cutting away of the lava here has exposed a section of the flow, 



