HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 95 



tion. Walcott's section^ is inverted, as originally published, and is here 

 given in the natural order, as follows : 



Big Cottonwood Section 



Feet 

 14. Superformatiou : Mixed saudy and calcareous rocks which rest con- 

 formably on 13 of the section and carry a fauna which refers it 

 to the lower Silurian (Ord). 



13. Hard, silico-argillaceous shales, a little sandy in places 250 



Fossils : At the base, Criiziana sp. associated with Olenellus 

 gilherti; 100 feet higher up, a band of shale afforded Linguella 

 ella, Kutorgina panula, Hyolitlies hillingsi, Leperdita argenta, 

 Ptychoparia quadrans and Batliyuriscus prodiicta. 



12. Gray compact quartzitic sandstone 3,000 



11. Purplish and reddish bix)\NTi quartzitic sandstone 75 



10. Gray compact quartzitic sandstone 700 



9. Black, sandy, arenaceous, slightly micaceous shale 75 



8. Light gray quartzite and quartzitic sandstone, in layers varying from 

 10 feet to 2 inches, the thin layers occurring as partings between 

 the more massive bands of layers. In some places, the quartzitic 

 sandstones show grains, and in others they are lost. Stains of 



purple, iron rust, reddish brown and buff color occur 2,700 



7. Arenaceous and argillaceous slates, black, bluish black, drab and 

 yellowish green. The exposure is extensive, the opportunity for 

 finding fossils excellent, and the slates afford a beautiful matrix 



for their preservation, but none were oben^ed 700 



6. Light gray quartzite and quartzitic sandstone, in laj'ers varying from 

 10 feet to 2 inches. In some places, the quartzitic sandstones show 

 grains, and in others they are lost. Stains of purple, iron rust, 



reddish brown and buff color occur 200 



5. Hard, black, arenaceous shale, with specks of mica on the surfaces. 



Quartzite and shale intercalated near the base 1,000 



4. Light gray quartzite and quartzitic sandstone in layers, varying from 

 10 feet to 2 inches. In some places, the quartzitic sandstones show 

 grains, and in others they are lost. Stains of purple, iron rust, 



reddish brown and buff color occur 700 



3. Purplish, thin bedded sandstone, with bands of greenish yellow argil- 

 laceous shale near the summit 700 



2. Massive bedded light gi*ay quartzite 1,000 



1. Black arenaceous shale, showing mud-mnrkings and mud cracks, 



ripple marks 900 



Total 12,000 



Age of Series 



From the occurrence of the Olenellus fauna in the shale member at the 

 top of the series and the apparent conformity of the entire succession of 



® The section is given here as corrected by Dr. VTalcott in his Correlation Papers, Bull. 

 U. S. Geol. Surv. No. 81, p. 319. 1891. 



