F. Quartz-basalt, one-half mile south of Cinder Cone, on border of lava field. Analysis by Hillebrand, No. 666.

G. Quartz-basalt, west end of Lake Bidwell, on border of Cinder Cone lava field. Contains a few grains of quartz, much olivine and plagioclase, less pyroxene, and a globulitic base. Analysis by Hillebrand, No. 661.

H. Quartz-basalt, Silver Lake, near Lassen Peak. Contains occasional grains of quartz, much feldspar and olivine, less pyroxene, and a brownish base. Analysis by Hillebrand, No. 662.

I. Quartz-basalt, resting on dacite, near west base of Lassen Peak. Analysis by Hillebrand, No. 677.

J. Quartz-basalt, island of Mitylene, coast of Asia Minor. Analysis for comparison with the Cinder Cone series, by T. M. Chatard, record No. 845.

Rocks F to I dried at 100° to 110° before analysis.

K. Recent basalt, Pit River. Rich in feldspar and augite, poor in olivine. Partial analysis by F. W. Clarke, record No. 109.

L. Basalt, 1 mile southeast of Paynes Creek, on the road from Red Bluff to Lassen Peak. A normal basalt, rather rich in olivine. Analysis by T. M. Chatard, record No. 405.

M. Basalt, summit of Inskip Crater, 25 miles east of Red Bluff. Mainly feldspar and augite, with a few phenocrysts of olivine. Analysis by Hillebrand and Chatard, record No. 406.

N. Basalt from the cone at south base of Burney Butte, Shasta County. Composed of plagioclase and augite, with some olivine and a globulitic base. Analysis by R. B. Riggs, record No. 685.

O. Basalt, near eastern end of rim of Crater Peak, Shasta County. Contains plagioclase and pyroxene, some of the latter being hypersthene with a trace of olivine. Analysis by R. B. Riggs, record No. 682.

P. Hornblende-basalt, Kosk Creek, near its mouth, by the great bend of Pit River, Shasta County. Contains abundant phenocrysts of hornblende, with a few of plagioclase, pyroxene, and olivine, in a groundmass of plagioclase, augite, and magnetite. The hornblendes are deeply corroded, and some have disappeared, leaving groups of magnetite grains to mark their former presence. Analysis by L. G. Eakins, record No. 1022. Described by Diller in Amer. Geologist, vol. 19, p.

253.

Rocks dried at 105° to 110° before analysis, except in the case of the rock marked L.

3. PLUMAS COUNTY.

Other rocks from this county are described under the heading of the Lassen Peak area. The following rocks, with two exceptions, were collected by H. W. Turner, who supplies the descriptions:

A. Granite, dike in serpentine, south slope of Grizzly Hill. Described by Turner in Amer. Geologist, vol. 17, p. 375. Contains quartz, albite, and muscovite. Analysis by H. N. Stokes, record No. 1562. P. R. C. 757.

B. Meta-rhyolite, near Tower Rock, Grizzly Mountains. Described by Turner in 14th Ann., p. 441. Contains porphyritic quartz, feldspar, and pyrite, in a fine groundmass. Analysis by W. F. Hillebrand, record No. 1273. P. R. C. 741.

C. Meta-rhyolite, near Greenville. Collected by Diller, who finds phenocrysts of quartz in a groundmass chiefly of quartz and feldspar. Analysis by Hillebrand, record No. 1458.

D. Granodiorite, southwest base of Mount Ingalls. Description supplied by Turner. Contains plagioclase, quartz, orthoclase, brown mica, green hornblende, iron oxide, and a little apatite, sphene, and epidote. Analysis by Hillebrand, record No. 1456. P. R. C. 727.

E. Granodiorite, Spanish Peak. Description supplied by Turner. Contains plagioclase, quartz, orthoclase, biotite, hornblende, iron ore, and apatite; also abundant secondary epidote and chlorite. Analysis by Stokes, record No. 1562. P. R. C. 756.

F. Rhyolite, 34 miles southwest of Grizzly Peak. Description furnished by Turner. Contains sanidine, with less quartz and biotite, in a glassy groundmass. Analysis by Hillebrand, record No. 1461. P. R. C. 776.

G. Hornblende-andesite, 4 miles from Pilot Peak. Described by Turner in 14th Ann., p. 441. Contains plagioclase and hornblende in a groundmass carrying grains of magnetite. Analysis by Hillebrand, record No. 1432. P. R. C. 716.

H. Hornblende-pyroxene-andesite, southwest base of Mount Ingalls. Description supplied by Turner. Contains plagioclase, rhombic pyroxene, augite, brown hornblende, and magnetite, with much glass in the groundmass. Analysis by Hillebrand, record No. 1456. P. R. C. 728. I. Hypersthene-andesite, Franklin Hill. Description supplied by Turner. Contains plagioclase, rhombic pyroxene, augite, and magnetite. Probably no glass. Analysis by Hillebrand, record No. 1548. P. R. C. 754.

J. Dolerite, Mount Ingalls. Described by Turner in 14th Ann., p. 441. Contains plagioclase, augite, hypersthene, magnetite, and a few olivines. Analysis by W. F. Hillebrand, record No. 1273. P. R. C. 739. K. Dolerite, Mount Ingalls. Also in 14th Ann., p. 441. Like J, but with scarcely any olivine. Analysis by Hillebrand, record No.

1432. P. R. C. 740.

L. Basalt, 4 miles southeast of Mount Ingalls. Also in 14th Ann., p. 441. Contains plagioclase, olivine, augite, and magnetite. Analysis by Hillebrand, record No. 1273.

M. Olivine-basalt, 14 miles from Franklin Hill. Contains plagioclase, augite, partly altered olivine, magnetite, and probably some glass. Description supplied by Turner. Analysis by George Steiger, record No. 1596. P. R. C. 755.

N. Serpentine, Greenville. Described by Diller in Bull. 150, p. 372. Besides serpentine, the rock contains some magnetite and less chromite, with remnants of the pyroxene from which the serpentine was in great part derived. Analysis by W. H. Melville, record No. 1346. P. R. C. 145.