Bitter — Mesozoic Sediments of Southwestern Oregon. 407 



appear to be intrusive, but the contacts are obscure and the 

 exact relations a matter of doubt. 



The borders of the G-aKce area are generally lines of displace- 

 ment. Along the eastern border of the area, on Rogue River, 

 a short distance below Massie's ferry, the slates are so greatly 

 sheared in the plane of general slaty cleavage dipping to the 

 southeast as to indicate decided displacement. 



On Grave Creek, near Anderson's, 5 miles below Leland, the 

 eastern border is an irregular fault which is locally exposed 

 and at least in part vertical. The general dip of the Galice 

 strata of that vicinity is to the southeast, and the topmost slates 

 are greatly sheared in the same direction as if volcanics were 

 ovdrthrust from the southeast. 



On Cow Creek, near the mouth of Rattlesnake, the contact 

 of the Galice slates and the volcanics is exposed within a few 

 square rods on three lines, all of which run approximately 

 northeast and southwest parallel to the strike of the slaty cleav- 

 age. Two of the contacts are clearly fault planes, straight and 

 smooth with slicken sides and local polish. These two lines of 

 evident displacement can be traced only about a score of feet 

 and run out into the volcanics. The third line of contact 

 which lies between the other two is much less regular. Though 

 the projecting portions of the volcanics along the line are 

 rounded as if by some form of attrition, it is not so clearly a 

 line of faulting. Wherever the contact of the Galice forma- 

 tion and the volcanics is exposed about the Galice area it 

 shows displacement, but the amount of the displacement and 

 its full meaning are not yet fully comprehended. It seems 

 certain, however, that the Galice formation in its present posi- 

 tion stratigraphically overlies a great portion of the associated 

 volcanics. 



Dothan Formation (Jurassic). 



Definition. — The Dothan formation is an extensive succes- 

 sion of conformable Jurassic sandstones and shales in which 

 the strata though often thin-bedded frequently range from 10 

 to over 100 feet in thickness. The sandstones predominate 

 and locally there are thin beds of fine conglomerate and small 

 lentils of radiolarian chert. The name is adopted from Dothan 

 post-office on Cow Creek, in the midst of one of the best 

 sections of the formation. 



Lithological features. The shales are gray, dark within, 

 rarely black. For the most part they are not slaty. At other 

 places they may be slickensided parallel to cleavage. The 

 sandstones are gray, weathering yellowish brown. They are 

 in the main firmly lithified with silica, and in some places so 

 squeezed as to give rise to a schistose structure with numerous 



