GEOLOGY OF THE KILDEER MOUNTAINS 265 
or wanting in these deposits, none being found in spite of diligent 
search. Only three places were found where the contact between 
the Fort Union formation and the beds above is exposed. A dis- 
crepancy of 41 feet between the elevations of these places shows 
that the contact is uneven. Furthermore it is apparent that the 
Fort Union rocks were oxidized and eroded before the deposition 
of the basal unoxidized stratum of the overlying formation. 
A generalized composite section of the younger formation, 
worked out from eight partial sections, is as follows: 
WHITE RIVER FORMATION, KILDEER MOUNTAINS, NORTH DAKOTA 
7. Pale-green, fine-grained, calcareous sandstone, interstratified 
with subordinate amounts of marl, hard layers of white limestone, 
and lenses of green, cherty sandstone. 97 feet. 
6. Upper hard ledge, a layer of ash-gray, arenaceous limestone. 
In the southern part of the mountains there are green, cherty lenses ~ 
and layers of quartzite within this calcareous member. 6 feet. 
5. Chalklike, soft, arenaceous marl. 64 feet. 
4. Middle hard ledge, upholding the main plateaus. Greenish- 
gray, white weathering, interstratified limestone and friable sand- 
stone. Rootlike stringers of white calcium carbonate join the 
layers of limestone through the sandy layers. In the north part 
of the mountains the ledge is almost solid limestone; in the southern 
outcrops the rock is sandy, porous, and apparently made up of 
grains of limestone and silica. 30 feet. 
3. Pale-green, friable, cross-bedded sandstone. In the southern 
outcrops it appears to be wind laid, but at the north end there are 
several layers of limestone with the sand. 30 feet. 
2. Lower hard ledge, a layer of pale-green, fine-grained, cal- 
careous sandstone, much like the middle hard ledge, but it is lime- 
stone near the north end of the mountains. ro feet. 
1. Green, crumbly, non-plastic clays, and green, fine and coarse, 
uncemented sands. At the southern end of the mountains there 
is a pebbly conglomerate layer one foot thick near the base of the 
member, and in a calcareous phase there are pebbles of limestone, 
quartz, and granite scattered sparsely throughout the rock. 170 
feet. 
