The oldest rocks exposed in the area are Upper Triassic sediments and volcanics of the Lewes River series. They are overlain, apparently with slight unconformity, by Jurassic clastic sediments of the Laberge series. A small area of coal-bearing rocks probably belongs to the Tantalus formation. Acid and basic volcanics of the Hutshi group overlie the Laberge series unconformably along the northern border of the area. Rocks of all the above groups are intruded by the Coast Range granitic intrusions. Greenstones and more highly metamorphosed rocks associated with the main intrusive complex appear to have been derived mainly from the Lewes River series. Flows of fresh basalt exposed in the southern part of the area are believed to be Tertiary in age. Evidence regarding the relation of the weathering to the glaciation is inconclusive and hence it is not known if the weathering is connected with the cool dry climate now prevailing at Whitehorse. Certain granitic rocks of the area appear to weather more readily than others. A study of mineralogy, texture and porosity of the main types of granitic rocks of the area shows that those granitic rocks that appear to be especially susceptible to weathering contain larger pores than less readily weathered granitic rocks, and it is suggested that this feature may partly explain the observed difference in weathering.
This thesis is available online at https://open.library.ubc.ca/cIRcle/collections/ubctheses/831/items/1.0053519. A copy of this thesis is available at the EMR library – QE195 F9.
