Diller — Mesozoic Sediments of Southwestern Oregon. 405 



On O'Sliea Creek only Aucella erringtoni was found. The 

 same form occurs with Belemnites by the stage road from 

 Grant's Pass to Crescent City, on Shelly and Monkey Creeks. 



In the field, the three areas of the Galice formation noted 

 above were regarded as Jurassic, and Dr. Stanton remarks that 

 '' the examination of the fossils has confirmed this view, 

 although the evidence is not as strong as might be desired. In 

 most cases the determination is based on the occurrence of a 

 form of Aucella with numerous distinct radiating striae which 

 I have identified with Aucella erringtoni, a common species of 

 the Mariposa slates in California. The Aucellae of the Lower 

 Cretaceous Knoxville beds often have nearly the same outlines, 

 but they never show the distinctive surface sculpture above 

 mentioned. So far as our present knowledge goes, therefore, 

 we are justified in assigning all beds containing Aucellae with 

 numerous fine radiating striae to the Jurassic. In two of the 

 lots, 6682 (Anderson's ditch) and 6687 (Almeda mine), this 

 reference is strengthened by the presence of Ammonites of 

 Jurassic type. This is especially true of 6687, which contains 

 a Perisphinctes very closely related to or possibly identical 

 with the Mariposa species doubtfully referred by Hyatt to 

 P. fliplex. The Perisphinctes (?) in lot 6682 is of a different 

 group which also resembles European Jurassic forms." 



Four lots from Galice, Grave and Rattlesnake creeks " all 

 contain poorly preserved specimens of Aucella that do not show 

 the surface features well enough for specific identification, 

 though from the character of the matrix and from their rela- 

 tions with the lots containing Aucella erringtoni, it is prob- 

 able they are Jurassic. 



Four lots from Shelly and Monkey creeks " are probably 

 also Jurassic as the Aucellae though not very well preserved 

 seem to have the striated surface in most of the lots." 



Structure of Galice area. — Notwithstanding the fact that 

 there are three good sections of the Galice area afforded by 

 .Rattlesnake Creek, Grave Creek and Rogue River, its struc- 

 ture and relation to the associated volcanic rocks are not clearly 

 understood. Along the main stream and East Fork of Rattle- 

 snake the position of the strata suggests a synclinal structure 

 for the belt, with the western arm well marked but the eastern 

 one less regular and indefinite. This is due at least in some 

 measure to the fact that in the eastern arm the slaty cleavage 

 makes a large angle with the stratification and tends to obscure 

 it. Where the strata strike N. 45° W. and dip 50° S.W., the 

 slaty cleavage strikes JN. 55° E. and dips 50° S.E. The slaty 

 cleavage throughout the area with but few doubtful exceptions 

 dips to the S.E. more or less steeply, and is generally much 

 more distinctly marked than the stratification. 



