Vol. VI] WEAVER— POST-EOCENE OF WESTERN WASHINGTON 27 



faunas collected from the type localities of the Twin River 

 and Seattle formations do not indicate sufficient grounds for 

 making a separation. The Seattle formation is described as 

 occurring on the south shore of the Strait of Juan de Fuca 

 east of Twin River and east of Gettysburg. Detailed mapping 

 in this region shows conclusively that the strata occurring 

 there are involved in tlie east and west limbs of a syncline, 

 and stratigraphical measurements prove the strata in 

 question on each limb of this syncline to be identical. 

 The arguments which have just been made concern- 

 ing the use of the term San Lorenzo in Washing- 

 ton, at present at least, may be applied to the introduction 

 of the term Monterey and Empire. The exact use of the term 

 Monterey has not been definitely agreed upon in California. 

 As more and more detailed information is obtained there is 

 divergence of opinion as to what is to be included within the 

 meaning of the term Monterey. The faunas of Washington 

 and Oregon are not at present sufficiently known to permit 

 any direct correlations. Suggestions can be made, but it would 

 seem preferable to the writer to use local names provisionally 

 and to gather all the information possible concerning forma- 

 tions or faunal zones in Washington and later, when such in- 

 formation is at hand, both in California and Washington, to 

 make direct correlations. Misunderstandings as to what the 

 writers are intending to convey will be less common. The 

 gathering and recording of accurate information in the field 

 is much more desirable than the attempt to make broad cor- 

 relations with distant areas on insufficient and imperfect field 

 data. After detailed studies have been made, such correla- 

 tions can be made with confidence. In the meantime suggested 

 similarities can be placed on record. 



Five distinct faunal zones can be recognized in the post- 

 Tejon strata of western Washington. The following table 

 will illustrate their sequence : 



Montesano horizon — Yoldia strigata zone. . . .Upper Miocene 

 — unconformity — 



Wahkiakum horizon — Area montereyana zone . Lower Miocene 

 — unconformity — 



