ANTLER PEAK. 21 



micaceous beds containing indistinct traces of fossils. The following section 

 was made at this place: 



Indian Creek section. 



Crowfoot Norn- 

 section, ber. Feet. 

 Laccolith, andesite-porphyry. 



11 6. Limestone, rather thinly bedded, dark blue-gray with lighter weathered surface. 6 



7-10 5. Limestones, forming the great ledge of the mountain side. Many beds are of a 



crystalline, fine-grained, dark-gray and dense limestone seamed with calcite. 



Weathers light gray, often rusty. At the base is thinly bedded, breaking 



readily into small angular pieces. At top, beds are slightly cherty and fossil- 



iferous. In center, beds are massive and appear irregularly bedded. Strike 



N. 54° E. and dip 3° N 225 



Dacite-porphyry, probably an offshoot of the Holmes bysmalith 25 



6 4. Limestone, compact, brown, weathering gray 20 



5 3. Shaly beds, micaceous and schistose, with thin bands of limestone 50 



2-4 2. Interval, no exposure 300 



1 1. Gneiss. 



It will be seen from the above section that the andesite-porphyry of 

 the laccolith immediately overlies the limestone No. 6 of this section, which 

 corresponds to the Flathead limestones of the Crowfoot Ridge section. 

 The laccolith has therefore been intruded in the upper shale belt of the 

 Flathead formation, the shales being 150 feet thick in the Crowfoot section. 

 The occurrence of the laccolithic intrusion is the same at the base of Three 

 River Peak, where above the porphyry a part of the shales is found 

 beneath the limestones that form the highest beds of the Flathead forma- 

 tion. 



At Antler Peak the laccolith incloses parts of the Flathead limestones, 

 as well as a thin belt of limestone and fragments of the underlying shale. 

 Along the base of steeper slopes toward the northeast, the drift has covered 

 all exposures; even the beds of the great limestone ledge are partially 

 hidden. Over these beds we find a platform where the overlying shale and 

 porphyry have been eroded, leaving the limestones underneath intact. That 

 the bench is due to the erosion of the shale seems probable; easily yield- 

 ing to disintegrating agencies, it has been carried away, undermining the 

 porphyry, which has also been swept off by glacial action. 



The lowest bed noted above the laccolith is a finely crystalline, light- 

 drab limestone, probably the upper beds of the Flathead limestone of the 

 general section. The following succession of strata is exposed on the 

 northeast spur of the mountain from the summit of the peak down to this 

 bed: 



