Ravalli Group (Spokane, Empire and Greyson Formations) of 

 Proterozoic (Belt) age. Nearby areas are shown as underlain by 

 granodiorite of Late Cretaceous age and by intermediate to mafic 

 volcanic rocks of Eocene and Oligocene (early to mid Tertiary) age. 

 [Mineralization can be inferred from the presence of the intrusive 

 body and from the local name "Mineral Hill".] 



Brush Lake and White Lake 



Bibliographic source: Montana Bureau of Mines and Geology 

 Publications Index 



Author: Reiten, J.C. 



Title: Water quality of selected lakes in Sheridan County, Montana 



Series: MBMG Open-file report 244 



Date: 1991(?) 



This publication describes the results of a 1990 survey of the 

 water quality of more than 50 lakes in Sheridan County, with 

 comparisons to previous (1984) field surveys of lake specific 

 conductance. The lakes sampled include Brush Lake, Mallard Pond, 

 White Lake, North Goose, North Widgeon Slough and Lone Tree. 

 Limited geochemical interpretations include the development of an 

 empirical "contamination index" based on molar ratios of chloride 

 ion to other anions. 



A poor-quality map at approximately 1:125,000 scale shows 

 classification of the sampled lakes according to a 5 - class system 

 based on specific conductance. 



Bibliographic source: Montana Bureau of Mines and Geology 

 Publication Index 



Author : Donovan , J.J. 



Title: Ground-water geology and high-yield aquifers of 

 northeastern Montana. 



Series: MBMG Open-file report 209 



Date: 1988 



This document is the most current and comprehensive investigation 

 of the northeastern Montana gravel aquifers which interact with 

 many lakes and wetlands in the area, including the wetland sampling 

 program sites of Brush Lake, White Lake, Mallard Pond, Gaffney Lake 



13 



