Mkrkiam. ] 



John Day Basin, 



307 



3 < 

 I = 



s - .S 



2 O 



2" 



Fossil Remains. — The 

 fossil remains, including 



in part of the same age, but may 

 have accumulated in a different basin. 



At Rattlesnake Creek near Cot- 

 tonwood the Mascall is not less than 

 800 to [,000 feet thick. The beds 

 are made up largely of ash and tuff 

 and are generally light colored, 

 though there are some brownish and 

 reddish strata. Coarse detrital mate- 

 rials are generally absent from the 

 typical section on the north side of 

 the East Fork Valley. 



Six miles above Dayville there are 

 exposed along the south side of the 

 valley about 400-50ofeet of conglom- 

 erate, sand, ash, and tuff, forming a 

 syncline pitching to the southeast. 

 The steepest dip seen in the main 

 section here is about 30 , but at the 

 foot of the bluff there are some 

 exposures of gravel beds which are 

 nearly vertical. Pebbles from several 

 horizons in this section were exam- 

 ined, but none seemed to be derived 

 from the Columbia lava. Two other 

 exposures of gravel were seen some 

 miles west of this point, also on the 

 south side of the river. Whether 

 these beds are upper Mascall or 

 whether they belong in some other 

 formation is not clear to the writer. 

 Fragmentary leaf remains were found 

 about the middle of the section, and 

 sufficient material could possibly be 

 obtained there to throw some light 

 upon the age of the horizon. 

 Mascall formation has furnished many 

 those of mammals, testudinates, fish, and 



