246 University of California Publications in Geology [Vol. 9 



of widespread occurrence. The Empire Formation, of middle Mio- 

 cene age, unconformably overlies the Myrtle Formation. The rocks 

 of this series occupy two separate areas. The strata of one of these 

 areas outcrop along the ocean cliffs from Cape Blanco to a small 

 gulch one and one-half miles southeast, where they are unconform- 

 ably overlaid by later deposits. The other area outcrops along the 

 cliffs north of Blackiock Point to Floras Lake. Diller in mapping 

 this region considered that the Empire Formation extended contin- 

 uously from Cape Blanco to the mouth of Elk River, a distance of 

 two and one-half miles. This was an error, as will be shown later by 

 palaeontological evidence. The strata of this area dip with a uni- 

 form inclination from Cape Blanco southeast to the small gulch 

 already referred to. The lower members are composed of a yellow- 

 ish-gray sandstone. Above this there is a layer of tuff which is about 

 twenty feet in thickness. This tuff contains numerous leaf impres- 

 sions. The upper portion consists of whitish and yellow sandstone, 

 medium to fine-grained. A collection of fossils from these beds 

 warrants their correlation with the Empire Formation of Coos Bay. 

 Diller designated this formation as the Cape Blanco Beds. 



Immediately north of the small gulch, one and one-half miles 

 southeast of Cape Blanco, the uppermost strata of the Cape Blanco 

 Beds are unconformably overlain by a thick bed of conglomerate 

 which grades upward into a coarse brown sandstone, and finally 

 into blue-gray argillaceous sandstone. South of this gulch the cliffs 

 afford a complete section to the mouth of Elk River. The beds 

 exposed in this section can be separated lithologically into two 

 divisions: (1) a blue-gray argillaceous sandstone or mudstone which 

 is the same member as was found overlying the conglomerate on the 

 north side of the gulch; (2) a loose gray sand which is very similar 

 to the sand of the Upper San Pedro Series at San Pedro, California. 

 These two members extend the entire length of the section from the 

 gulch to the mouth of Elk River, where they dip beneath the beach 

 sand. The blue-gray argillaceous sandstone forms the base of the 

 cliffs for the entire distance. The loose gray sand overlies it con- 

 formably, both dipping at a very small angle to the south and east. 

 The difference between these two members is most noticeable in the 

 face of the cliff. The lower beds are consolidated and form a vertical 

 wall twenty or thirty feet in height. The overlying loose sand yields 

 easily to weathering and as a result a distinct angulation occurs in 

 the face of the cliff at this point. 



