3 o8 



the glaciated crystalline rocks, and is only a few feet in 

 thickness. It varies from an unstratified, hard, yellowish 

 gray, sandy clay, with subangular to rounded pebbles, 

 to rudely stratified, coarser, yellow clayey sand, with 

 scattered pebbles and subangular boulders. 



The Puyallup inter-glacial deposits are chiefly well 

 stratified clays, sands, and gravels usually found below 

 elevations of 250 feet (76 m.) In general, the clays 

 occur near the base of the deposits, and the sands and 

 gravels near the top, so the deposits are subdivided into 

 the May wood clays and the Cordova sands and gravels. 

 The Maywood clays are chiefly bluish or yellowish 

 gray, sandy clays with numerous, irregularly distributed, 

 subangular to rounded, undecomposed pebbles and boulders 

 of crystalline rocks. They are well stratified and fre- 

 quently contain layers of sand and occasionally of gravel. 

 The clays are frequently carbonaceous, and plant 

 impressions and remains are common in them. 

 Impressions and occasional shells of marine organisms, 

 chiefly small molluscs, are also found in them. The 

 Maywood clays sometimes rest upon the Admiralty till, 

 but more commonly lie directly on glaciated surface of the 

 crystalline rocks. They vary greatly in thickness, 

 depending partly upon the irregularities of the underlying 

 rock surface, but they probably average as much as 

 100 feet (30 m.). 



The Cordova sands and gravels consist of yellow to 

 grayish yellow, medium to coarse grained, and usually 

 pebbley sand, with irregular lentils and interbeds of 

 gravel, and towards the base, interbeds sometimes 10 to 

 15 feet (3 to 4-5 m.) thick of sandy clay or rarely stiff 

 blue clay. They also contain a few, irregularly distributed, 

 small glacial boulders. The pebbles are usually fresh, 

 but in some instances the coarser grained granitic pebbles 

 have been entirely decomposed. The sands are well 

 stratified, but are usually cross bedded, and exhibit instances 

 of contemporaneous erosion and deposition. They also 

 contain marine organisms, which are however very 

 fragile. The Cordova sands and gravels, averaging 200 feet 

 (65 m.) in thickness, overlie the Maywood clays, and 

 usually form low ridges that were left in relief by the 

 erosion of wide valleys between them by glaciers of the 

 Vashon period Some of the ridges occur in the lea of 

 the larger monadnocks. 



