SUMMARY 



331 



The most recent deposits of the area are Pleistocene stream and glacial 

 gravels. This formation is most extensively displayed near the head of 

 Mataniiska river, where the present stream gorge has cut through 300 or 

 400 feet of glacial gravels. 



Intrusive igneous Eocks 



In addition to the stratiform volcanics of Middle Jurassic and Tertiary 

 ages, igneous rocks of intrusive character are abundant in certain parts 

 of the region. Of these diabase dikes and sills are widely prevalent, 

 attaining a maximum thickness of 500 feet. They are intrusive into 

 rocks as late in age as the Kenai. 



The granular plutonics making up the central mass of the Talkeetna 

 mountains, however, possess far wider interest on account of their con- 

 nection with problems of great geological significance. They are chiefly 

 quartz-diorites carrying orthoclase, and are intrusive into rocks at least 

 of Lower Middle Jurassic age. They are thus contemporaneous with the 

 enormous batholithic intrusions of the late Mesozoic, which affected the 



ejxim Oovdillevm regioB from the strait of Magellan to the Beward 

 peBiaiiilft, ia sorthwiitera AIa§kg,* 



Thi foeki of ih§ arta iaveitigatitl faap ia ehajaetir ifQm |afflit= 

 ilii'Oii miea=§ehiit§ of pi'i=iiluriia ap to uneoaiolidatid Flsiiteeiai 

 itftaia aai flaeial |fav@l§. Thi rifioa, howi¥§3?, i§ ehiifly aottwerthy 

 §a aegeuat of thi eMteaiivi iiviiopsiiat of atiriat Jaf&siie itrata aad 

 thi pf liiaei of XJpp§? leetai ffi§h=wati? §§iiaitati earryiaf thiek giami 

 el bitiffliaoai eeal. 



f hi itfatifraphie eelaiaa laay hi lammariiid ai fellowi i 



gl§}§l§§§ae:=gti'§affl aag g\mm\ pav^lg: 



P§8l^i§§§a§:=la§alli§ lav&§ aag ps^reelagties-. ::•. = ::,:,...:,.,.,,,. 1,0Q0 =t= 

 Itggep i§§§ae:=Seiiai f§i'fflati§fii iaMiteflis, %M\m, aHfl e§aii§a= 



ePatei, Witfe @§al ieaai-. :::•.:=::!:::■.:::::■..•.•.■..::<. = .... = ,. 3,000 ^ 



9vu-?gy, 



