Vol. VI] WEAVER— EOCENE OF LOWER COWLITZ VALLEY 7 



Top of Section Feet 



Banded sandstone and shale as exposed at the town of Winlock 

 and in the banks of Olequah Creek to the west and northwest 

 of town. The fauna occurring at Locality No. 229 is charac- 

 teristic of this zone 500 



Massive clay shale grading in places into sandy shale as exposed 

 along the banks of Olequah Creek south of Winlock and also 

 in the bank of Cowlitz River in Section 5, Township 11 North, 

 Range 2 West, at fossil Locality No. 239 (locally known as the 

 Gracco Ranch). This is the base of the Oligocene in this 

 region 600 



Top of Eocene section. Chiefly sandy shale grading into massive 

 clay shale of a dark brow^nish gray color. Exposures repre- 

 senting this phase are not very abundant but contain occa- 

 sional specimens of Venericardia planicosta Lamarck and Tur- 

 ritella uvasana Conrad 960 



Shaly sandstone 100 



Slightly banded sandy shale 130 



Slightly carbonaceous sandy shale 50 



Sandy shale 430 



Laminated sandstone and sandy shale 150 



Shale, slightly sandy. The upper part of this zone contains an 



abundant marine Tejon fauna 340 



Massive clay shale containing the fauna at Localities Nos. 1, la, 

 232 and 233, in the north bank of Cowlitz River, Section 25, 

 Township 1 1 North, Range 2 West SO 



Sandy clay shale. This is the base of the upper marine division of 



the section 70 



Brackish water zone. Yellowish brown sandstone vdth interbedded 

 lignitic layers. These sandstones often grade into carbonace- 

 ous sandy shales 520 



Freshwater zone. Light gray massive clay shale, containing numer- 

 ous freshwater Eocene invertebrates. Fossil Localities Nos. 

 295 and 303 occur in these shales 130 



Lower brackish water zone. Sandy shales and shaly sandstones 

 often grading into brownish yellow coarse grained sandstones. 

 All are more or less carbonaceous. Fossil Localities Nos. 

 231, 234 and 300 occur within this zone 550 



Lower marine zone. Sandy clay shales grading into shalv sand- 

 stones. Fossil Localities Nos. 240, 240b, 299, 241, 238, 301, 

 236, 298, 294 and 294a occur within this zone. The basal por- 

 tion of this belt contains a few very narrow layers of brackish 

 water sediments. Below this belt no detailed measurements of 

 the strata have been made. The underlying strata are those in- 

 volved in the area between Castle Rock and Olequah. Just 

 below the base of these marine beds, flows of basalt and de- 

 posits of basaltic tuff are intercallated with the sediments, 

 which appear to be predominatingly of brackish water origin. . 390 



Total thickness of measured strata between Olequah and Win- 

 lock 4,970 



Possible thickness of unmeasured strata involved in area between 



Castle Rock and Olequah 6,000 



Possible total thickness of Eocene as exposed in the lower Cow- 

 litz Valley section 10,970 



