IGNEOUS AND CRYSTALLINE ROCKS. sl 
5.30 4, 36 4.19 4.75 
3.99 3.20 4.15 3. 90 
12 «12 08 44 
32 -78 h4 97 
33 -50 51 73 
33 - 20 23 63 
trace | trace | trace trace 
05 - 08 
29 34 30 32 
100.01 | 100.00 | 100.11 | 100.26 
G. Porphyrite, intrusive sheet, north of Shields River basin. Akerose. Contains 
plagioclase, hornblende, and biotite, in a groundmass of plagioclase, a little orthoclase, 
augite, hornblende, and magnetite. P. R. (|. 1726. 
H. Porphyrite, intrusive sheet, northern part of the mountains. Akerose. Contains 
brown hornblende, green augite, and plagioclase, in a groundmass of plagioclase, augite, 
and magnetite, with accessory apatite. P.R.('. 1727. 
I. Syenite, ridge north of Shields River basin. Akerose. Contains hornblende, 
green augite, and anorthoclase, with accessory sphene, apatite, and magnetite. P. R. 
C. 1728. 
J. Diabase-porphyrite (?), dike south of Shields River basin. J. 5. 3.4. Contains 
labradorite and decomposed augite in a groundmass of plagioclase, epidote, and 
chlorite. P.R.C. 1729. 
K. Diorite-porphyrite, Big Timber Creek. Andose. Contains labradorite, augite, 
hornblende, biotite, orthoclase, quartz, magnetite, and apatite. P. R. (. 1730. 
L. Quartz diorite, main stock on Sweet Grass Creek. Andose. Contains hornblende, 
biotite, augite, labradorite, orthoclase, and quartz, with accessory apatite, magnetite, 
olivine, and hypersthene. P. R. (. 1731. 
M. Diorite, head of Rock Creck. Shoshonose. Contains biotite, labradorite, and 
augite, in a groundmass of plagioclase, orthoclase, and quartz, with accessory mag- 
netite, apatite, and hornblende. P. R. (. 1732. 
N. Diorite, main stock, Big Timber Creck. Andose. Contains biotite, augite, 
labradorite, quartz, orthoclase, apatite, and magnetite. P. R. (. 1733. 
