96 WARREN DUPRE SMITH AND EARL L. PACKARD 



and Tillamook counties, and at Eugene, Lane County. These 

 and other less well-known localities indicate that the Oligocene is 

 quite extensively developed throughout northwestern Oregon, 

 eastward to the foothills of the Cascades, and at least as far south 

 as Eugene. Much remains to be done in connecting, or correlating, 

 these rather isolated areas. 



These Oligocene strata, aggregating several hundred feet, 

 consist of marine shales, sandstones, conglomerates, tuffs, and 

 basaltic intrusives, varying considerably in character from locality 

 to locality. 



The Oligocene marine fauna of Oregon is but imperfectly known, 

 the Molopophorous lincolnensis and the Acila gettyshurgensis zones 

 of Washington being certainly recognized. 



The upper Oligocene is well developed within the John Day 

 Valley, where some 1,500 feet of sedimentaries are known as the 

 John Day series. It is well exposed along the valleys of the John 

 Day from Picture Gorge to Clarno, and along the North Fork to a 

 point some distance above Monument. Other isolated localities 

 are known outside the John Day drainage basin. The series is 

 divisible into three lithologic and paleontologic divisions, the lower 

 of which is characteristically composed of red, green, or white 

 shales ; the middle division by drab and bluish tuffs ; and the upper 

 by buff tuffs, rhyolite, sands, and gravels. These terrestrial beds 

 are but httle deformed, dips of 5 to 10 degrees being rather excep- 

 tional. 



The remarkable vertebrate fauna is confined to the two upper 

 divisions, the middle yielding a Diceratherium zone fauna of over 

 fifty species. The upper fauna is that of the Promerycochoerus 

 zone. This John Day fauna of over one hundred species is corre- 

 lated with the upper portion of the White River group. 



Neocene. — The Neocene of western Oregon is represented by a 

 series of sedimentaries yielding a lower or Monterey fauna, and an 

 upper or Empire-Merced fauna. The beds yielding the Monterey 

 fauna have not as yet been clearly differentiated from the Astoria 

 group, so that their distribution and geologic characteristics can 

 be given only in the most general terms. They include, in part, 

 the "Solon Beds" of Condon. The strata at these localities con- 



