in the Triassic of Worth America. 



93 



Triassic Section of Shasta County, California. 



Thickness 



0) 

 Pa 

 ft 



3-2 « 





M 



p ai 



03 



Black slates, with Pseudomonotis subcircularis. 



Spiriferina beds, hard siliceous limestone, full of 

 brachiopods. 



Coral zone, with numerous reefs, of Astrseidse, 

 Isastrcea, Stephanoccenia, Astrocoenia, Tham- 

 nastroea, and Thecosmilia. 



Pi w 



Juvavites beds, hard limestone, with abundant 

 ammonites, Juvavites, Gonionotites, Disco- 

 phyllites, Tropites Telleri, T. laestrigonus, 

 etc. 



Trachyceras beds, shaly limestone, with Trop- 

 ites subbullatus, T. torquillus, T. Dilleri, 

 Discotropites sandlingensis, Paratropites, 

 Trachyceras Lecontei, T. shastense, etc. 



Halobia superba shales, calcareous shales, full of 

 Halobia superba, and a few crushed Trachyceras. 



Halobia rugosa slates, black argillites, with Halo- 

 bia rugosa, and crushed Trachyceras. 



Unconformity 



Black siliceous shales, altered tuffs, and igneous 

 rocks, with Ceratites conf. humboldtensis. 

 Ptychites, etc. 



Unconformity 



Nosoni tuffs and shaly limestones, with Fusulina 

 elongata, etc. 



McCloud limestone, with Fusulina robusta, F. 

 cylindrica, etc. 



? 800 ft. 



100 ft. 



50 ft. 



50 ft. 



100 ft. 



150 ft. 



1500 ft. 



Squaw Creek and Pitt River, to less than half so much on the 

 North Fork, 15 miles to the north, where the limestone 

 almost disappears entirely. 



The Tropites subbullatus beds are divided into two zones, each 

 about fifty feet thick. In the lower are numerous Tropites 

 subbullatus, T torquillus, T. Dilleri, T. Morloti, T. fuso- 

 bullatus, Discotropites sandlingensis, Trachyceras Lecontei, 

 T. shastense, Arcestes pacificus, Clionites, Halobia superba, 

 and many undescribed species of Tropites, Trachyceras, etc. 



In the higher division, the Juvavites or Atractites beds are 



