562 WARREN S. SMITH 



In the Pleistocene the Skykomish Basin was eroded by valley 

 glaciers, and the only discernible post-Tertiary volcanic history is 

 recorded in a thin layer of ash, probably drifted from Mt. Rainier 

 by prevailing southwest winds. Post-Pleistocene time has not 

 lasted long enough seriously to change the aspect of the topography 

 left by glaciation. 



II. PRE-TERTIARY HISTORY 

 PRE-MESOZOIC 



The pre-Mesozoic is represented by two divisions, one of which 

 is considerably older than the other, and on lithologic grounds is 

 referred to an equivalency with the Easton schist. The later 

 division has experienced at least one stage less of metamorphic 

 history and is of known Ordovician age, on the evidence of fossils 

 obtained from a cherty phase of the limestone lens outcropping 

 in Lowe Gulch (D 2), two miles west of Grotto. No evidence of 

 the exact age of the Easton schist has been put forth and none can 

 be suggested for the Skykomish Basin. It comprises extremely 

 metamorphosed and crumpled rocks generally derived from sedi- 

 ments. This structural condition of the rocks precludes any esti- 

 mate as to their original thickness, but does enable one to infer 

 that they are of considerably greater age than any other Paleozoic 

 division which is much less dynamically disturbed. 



MALONEY 



The Maloney comprises a series of metamorphosed rocks 

 including quartzites, limestones, and schists of sedimentary origin 

 cut by basic igneous rocks, usually best described as greenstones, 

 which are later in age than the Maloney, but which on the evidence 

 of their extreme metamorphism are considered to be also of Paleo- 

 zoic age. The name Maloney is applied to a series formerly believed 

 to be equivalent to the Peshastin series, which is called Carbonif- 

 erous in age. The evidence on which this correlation is made is 

 presented in an earlier paper. 1 Subsequent identification of fossils 

 found in the limestone lenses shows the formation to be Ordovician 

 in age, and therefore the name Maloney is suggested. 



1 Warren S. Smith, "Petrology and Economic Geology of the Skykomish Basin, 

 Washington," School of Mines Quarterly, XXXVI (1915), 157. 



