^9^3-1 STRATIGRAPHY OF PACIFIC COAST OF AMERICA. 571 



Locality 68; sandstone and tuffaceous marl, bluffs on Stillwater Creek at 

 old logdam and for one fourth of a mile below, Little Falls, Washington. 

 (H. Hannibal.) 



Locality 70; tuffaceous sandstone, bluffs along Stillwater Creek three 

 fourths of a mile west of junction with Olequa Creek, Little Falls, Washing- 

 ton. (H. Hannibal.) 



Locality 73; basalt tuff, cut on Portland-Tacoma railway two and one half 

 miles south of Little Falls, Washington. (H. Hannibal.) 



Locality 74; sandstone, gulch below Backstrom ranch. Brim Creek, Little 

 Falls, Washington. (H. Hannibal.) 



Locality 75; lignitic sandstone, bluffs three fourths of a mile above Con 

 Murphy ranch on Stillwater Creek, Little Falls, Washington. (H. Hannibal.) 



forms are present in the Swank formation at Liberty, Washington, 

 it is probable that the two deposits on opposite sides of the Cascade 

 Mountains are approximately contemporaneous. 



An excellent plant locality in the Olequa formation occurs on 

 Olequa Creek above Little Falls, another is situated in the hills 

 west of Castle Rock. The plant localities at the Carbonado and 

 Wilkeston coal mines. South Prairie Creek above the Burnett Mine, 

 the Bellingham and Lake Whatcom mines, and near Maple Falls on 

 Mt. Baker may be referable to this horizon. 



The following marine fauna was collected on Olequa and Still- 

 water Creeks near Little Falls. 



Arago Formation. 



The type section of the Arago formation^^ is taken across the 

 strike of a steeply tilted fault-block which may be estimated to in- 

 clude approximately 10,000 feet of alternating marine and fresh- 

 water sediments, partly arkose and partly tuffaceous in character, 

 without the base or top of the formation being exposed. A much 

 larger area in which more than 15,000 feet of sediments are repre- 

 sented extends eastward from Coos Bay to the base of the Cascade 

 Mountains and northward along the west flank of the Cascades and 

 through the heart of the Coast Range, besides underlying and out- 

 cropping in the Willamette Valley across which the formation was 

 once continuous. In the northward extension of the Arago in 

 Oregon the sedimentary deposits become more and more replaced 



18 See J. S. Diller, Coos Bay Folio, No. 72, U. S. Geol. Sur., 1901. 



