782 ABSTRACTS OF PAPERS 



STRATIQBAPHIC RELATIONS OF THE LIVINGSTON BEDS OF CENTRAL 



MONTANA 



BY B. W. STONE AND W. R. CALVERT" 



(Al)stract) 



The Livingston formation occurring at Livingston, Montana, has been de- 

 scribed as resting unconformably on the Laramie and overlain by the Fort 

 Union formation. Its age has been considered to be post-Laramie and it has 

 been correlated with the Denver formation of Colorado, partly on lithologic 

 similarity, both formations being composed largely of tufaceous beds. This 

 paper shows that the Laramie of the Livingston and Little Belt Mountains 

 folios of the Geological Atlas of the United States is Eagle, or at least lower 

 Montana, and that there is no unconformity between it and the overlying Liv- 

 ingston beds in the area under discussion. It shows also that on the west and 

 south sides of the Crazy Mountains about 7,000 feet of sediments, mainly 

 andesitic tuffs, lying between the Eagle and Fort Union formations, constitute 

 on lithologic grounds a single formation, but that on the north and east sides 

 of the Crazy Mountains these same tufaceous beds are intercalated in the 

 Colorado, Eagle, Claggett, Judith River, Bearpaw, "Laramie," and Fort Union 

 formations. In other words, the Livingston has no formational value and has 

 no definite age, for it represents volcanic activity which recurred throughout 

 late Cretaceous and early Tertiary time. 



DISCOVERY OF FOSSILS IN THE QUANTICO SLATE BELT, AND THE ASSOCIA- 

 TION OF VOLCANO-SEDIMENTARY BEDS WITH THE SLATES OF 

 THE VIRGINIA CRYSTALLINE REQION^^ 



BY THOMAS L. WATSON AND S. L. POWELL 



{Abstract) 



Recent field studies of the various slate areas in the crystalline (Piedmont) 

 region of Virginia by the State Geological Survey have resulted in much im- 

 portant information on the lithologic characters, structure, and age relations 

 of the rocks. Of especial interest are (1) the discovery of fossils in the east- 

 ernmost of the slate areas, and (2) the recognition of well defined volcano- 

 sedimentary beds in intimate association with the slates in several of the most 

 extensive areas. During the past season fossils were found a short distance 

 north of Dumfries, Prince William County, Virginia, in the Quantico slate belt, 

 which are shown to be closely related to Cincinnatian forms. In 1892 Mr. 

 Darton announced the discovery of fossils in the Arvonia slates of Bucking- 

 ham County, Virginia, which were determined by Mr. Walcott to be upper 

 Ordovician. From the evidence of organic remains, these two areas, separated 

 by a considerable distance, though aligned approximately on the same strike, 

 are shown to be of the same age — Cincinnatian. 



« Introduced by M. R. Campbell 



" Read by title, In the absence of the authors. 



