STRATIGRAPHY OF THE SKYKOMISH BASIN, 

 WASHINGTON 



WARREN S. SMITH 

 Berlin, Washington 



WITH 



REPORT UPON PALEONTOLOGY AND PALEOPHYTOLOGY 



CAROLINE A. DUROR 



STRATIGRAPHY 

 I. GENERAL AREAL DISTRIBUTION 



In general, the rocks of the Skykomish Basin trend in a north- 

 south direction. This is almost exactly true of the igneous and 

 metamorphic terranes. Only the sedimentary Swauk and the 

 tufaceous Keechelus series vary from this general statement, for 

 they show a trend in general west of north but bending northward 

 on their northern prolongation. Dawson has remarked this tend- 

 ency of all the rocks of the Cordilleran system. 1 The rocks lie 

 in roughly parallel bands in the north, but are replaced southward 

 until the granodiorite entirely takes the place of the earlier series 

 and extends over nearly the entire width of the quadrangle. Igne- 

 ous rocks greatly predominate in the area, metamorphics and 

 sedimentaries being approximately equal in amount, and both 

 being comparatively small. Volcanics make up a smaller division. 

 These relations will be illustrated by the following classification 



table : 



Snoqualmie granodiorite 130. 90 



Keechelus andesitic series 32 . 20 



Tye soda granite and Beckler stock 24. 15 



Easton schist 22.95 



Swauk sedimentary series 56 . 00 



Maloney metamorphic series 14. 80 



Index granodiorite 4. 35 



Surface outcrop areas 285 .35 sq. mi. 



'G. M. Dawson, "Geological Record of the Rocky Mountain Region in Canada," 

 Bu Geol. Soc. Am., XII (1901), 59. 



559 



