66 



GEOLOGY OF THE EUEEKA DISTEICT. 



Nevada limestone — Devonian. 



'm;;mm;w/m//mm 



■/WW. 'IWWW/WWWW/, 



nii»imiinm»ii»i}i/ii»i7. 



MODOC SECTION. 



(Dark gray to bluish black massive limestone poor in fossils ; qiiite well 

 bedded; weatlieriug partly smooth and dark colored; partly rough 

 and pitted and of lighter color; mostly compact and massive, also of 

 uneven texture ; with numerous calcite seams. 



( Light and dark colored limestone with Stromaiopora and Cha'tetes; 

 ■50 ( coutain.s two layers thinly bedded (fissile). 

 60 Compact light yellow sandstone. 



( Light and dark colored limestone in layers 10 to 20 feet thick, with 



( Stromaiopora and Chcstetes. 



'BO Dark colored limestone with Stromaiopora and Chaitetes. 



i Alternating layers (about 10 feet thick) of dark and light gray lime- 

 900 S stone, finely Ijanded and lined ; weathering brownish gray ; iu places 

 ( bearing Chateles. 



SO Compact yellow sandstone. 



ISO Dark and light gray limestone; indistinct bedding. 



so ( Compact yellow sand.stone. 



) Dark and lijrht colored limestone interbedded in layers from 4 to 10 

 2^0 feet thick. 



2 7Q Light gray siliceous limestone ; very siliceous near base. 



) Alternating beds of dark and light gray limestone; at base 30 feet; 

 /30 ^ very siliceous limestone ; with cross bedding on weathered surface. 

 ■3 Compact yellow sandstone. 



i Dark and light gray limestone iu thick belts of dark, lighter, and 

 ■^ \ gray colors. 



2ZS Dark dense limestone ; well bedded; bearing fossils. 

 200 Shaly limestone rich iu fossils. 



( Light gray siliceous limestone, with fine lines of bedding; in upper 

 SSO \ portion weathering in almost rectangular fragments; growing 

 f less siliceous toward the bottom. 



Uo Light gray highly crystalline, saccharoid dolomite; not siliceous. 



J400 

 Fio. 3.— Nevada limestone — Modoc 

 section. 



