Diller — Klamath Mountain Section, California. 345 



"Loc. 705 has Posidonomya (very common) and two species 

 of Ammonoids of the family Prolecanitidoe. Locality 704 (White 

 Rock) has the same species of Posidonomya as that of 705 and 

 with it is associated Stromat^pora and other fossils too obscure 

 to determine. The preservation of the ammonoids is such that one 

 cannot make a certain determination of them, and yet their asso- 

 ciation with Stromatopora and Posidonomya seems to warrant 

 the conclusion that the horizon of the limestone of 704 and 705 is 

 in the Upper Devonian." 



Associated with the small fossiliferous limestone, three-quar- 

 ters of a mile west of White Rock, is a small mass of red chert 

 with the usual round clear spots of murky silica, but no definite 

 radiolarian structure could be found. Shales and sandstones 

 are uncommon and much disturbed, but like the limestones 

 generally strike northwest and dip northeast. These limestone 

 lentils with others in the same strike occur within a few hun- 

 dred feet of the mica schist of South Fork Mountain, and their 

 outcrops were traced at intervals along this part of the South 

 Fork of Trinity for over 10 miles. 



Twenty miles further northwest we again examine the South 

 Fork limestone belt beginning near the mouth of Rattlesnake 

 Creek. 



From Rattlesnake Creek near its mouth northwestward for 

 several miles, there is a series of limestone lenses nearly in 

 line and increasing in size northward to a point where it forms 

 cliffs 100 feet in height. The outcrop has a length of about a 

 quarter of a mile and a thickness of 50 feet. On the steep slope 

 beneath the limestone cliff is a mass of basic igneous rock, part 

 of which like a lava flow is full of cavities while other parts 

 are volcanic conglomerate or tuff, In the conglomerate occur 

 large and small fragments of slightly fossiliferous limestone 

 (709a) like that of the main mass (709 and 710), as though the 

 fragments were broken off during an eruption. The limestone 

 mass itself is cut by an irregular body of the same igneous 

 rock. The general strike of the limestone is parallel to the 

 South Fork of Trinity, above which it rises 1,500 feet at a dis- 

 tance of over a mile. The rocks lying between the limestone 

 and schist at this point are largely altered by igneous rocks 

 and locally converted into hornfels. 



The rocks exposed about the limestone ledges are almost 

 wholly igneous of basic types related to gabbro and serpentine. 



The same belt of limestone becomes prominent again about 

 20 miles further northwest in township 2 N., R. 7 E., on the 

 summit of the divide west of Indian Creek. As at White 

 Rock the sparsely fossiliferous limestone (711) is much broken 

 up, covering acres of the gentler slope, and associated with it is 



