﻿9i Outctops 1 3 



abundant 10 



B. Drab shale, mostly covered ioo 



A. Lead-gray limestone, checked by innumerable small joints 



which are generally calcite filled 120 



In this section the gray and black limestone series is preceded 

 by beds holding a Cambrian fauna and followed by a limestone 

 holding the usual Madison limestone fauna. The shale formation 

 (I) at the top of the magnesian limestone formation appears to 

 occupy the position of the Threeforks shale, but it is barren of 

 fossils. Composition, texture, manner of weathering, and rela- 

 tionship to the section all indicate that the magnesian limestone 

 series of the section is the same formation as the Jefferson lime- 

 stone of the Montana sections. 



The Jefferson limestone of the Labarge Mountain section is 

 nearly barren of fossils. The only fossils obtained in it were. 

 Zaphrentis and fragments of another undetermined coral. The 

 gray limestone (C and F of the section) contains a fauna which 

 Mr. E. O. Ulrich reports to be of late Middle or basal UppeT 

 Cambrian age 7 . 



We are without positive information regarding the age of the 

 700 feet of gray limestones below the saccharoidal limestones of 

 the Jefferson. These beds (G of the section) may be in part of 

 the same formation and age as the 40 feet of limestone at their 

 base, the age of which is known by its fossils to be Cambrian. 

 It seems probable, however, that Silurian or Ordovician strata 

 or perhaps both may be included in the series. The Ordovician 

 is present in the Bighorn Mountains to the north, and both are 

 present in northeastern Utah. 



The Carboniferous limestones which comprise the two upper- 

 most divisions of the section contain a fauna representing the 

 Madison limestone fauna of Montana and Wyoming. Fossils 

 collected from the lower 100 feet of the beds marked J have been 

 determined by Dr. G. H. Girty as follows : 



Menophyllum excavatum 



Rhipidomella pulchella 



7 Letter to the writer dated February 11, 1908. 



