REPORT OF TEE CE1EF ASTRONOMER 471 



SESSIONAL PAPER No. 25a 



5. At the close of the Laramie period, revolutionary orogenie disturbance, 

 shearing and crushing the granodiorites and basic intrusives. In the former, 

 development of strong crush-foliation and banding with the formation of new 

 rock types, including biotite-epidote-hornblende gneiss, biotite-epidote gneiss, 

 basic hornblende gneiss, biotite schist, hornblende schist, and recrystallized 

 biotite granite-gneisses; in the basic intrusives, development of metagabbro and 

 various basic (dioritic) gneisses and hoimblendites. Simultaneous strong folding 

 of the Cretaceous strata. 



6. Either accompanying or following the post-Laramie deformation, the 

 (chonolithic ?) intrusion of the Krnger alkaline body, which consists of nearly 

 synchronous masses of nephelite syenite and malignite. In these at least ten 

 different rock types, due in part to the splitting of an alkaline magma and in 

 part to later dynamic metamorphism, have been recognized. 



7. In Tertiary time the batholithic irruption and complete crystallization 

 of the soda-rich Similkameen hornblende-biotite granite, its contact basification 

 forming soda-monzonites and quartz diorites. 



8. In later Tertiary time the batholithic irruption of the Cathedral biotite 

 granite, Older phase, accompanied by the intrusion of the Park Granite stock, 

 immediately followed by the injection of the Cathedral granite, Younger phase, 

 within the body of the Older phase. 



9. Removal by denudation of much of the cover over each intrusive body. 

 Complete destruction of the Cretaceous cover except at the Pasayten River 

 overlap. Certain dikes of olivine basalt injected into the Cathedral and other 

 granites are apparently of Pleistocene age and represent the latest products 

 of eruptive activity in the Okanagan range. The vesicular-andesite dikes cutting 

 the Basic Complex are probably as recent. The porphyrite dikes cutting the 

 Similkameen batholith are possibly contemporaneous with these basaltic and 

 andesitic injections. These dikes are quantitatively of little importance in the 

 development of the composite batholith itself. 



SEQUENCE OP THE ERUPTIVE ROCKS. 



The reference of the different batholithic members to definite geological 

 periods is tentative and still gives grounds for debate, but the relative order 

 in which the component bodies were intruded is largely, and so far finally, 

 determined. In very few other parts of the world are the conditions so favour- 

 able for tracing out the succession in time of an equal number of large-scale 

 intrusive bodies. It is therefore expedient to note the sequence of the eruptive 

 rocks in the Okanagan batholith. The writer believes that a careful study of 

 the sequence here and in similar batholithic provinces can yield valuable results 

 affecting the theory of granitic intrusion. 



Of the available chemical analyses those which most typically represent the 

 original composition of the various component bodies have been noted in Table 

 XXX. In that table the analyses are arranged from left to right in the order 



