PLUGS

371. .1 Volcanic neck. The "Stock" or root of an ancient eruption. Mato-Tepe, Wyo.
371. .2 Pic du Capucin, Valley of Dordogne, near Mt. Dore, Auvergne, France.
371. .3 A volcanic plug. Bear Butte, Wyoming, from west near Black Hills.
371. .4 Volcanic plug. Starks' Knob, Schuylerville, N.Y., from southeast, after partial quarrying. September 1, 1910. H.P.C.
371. .5 Volcanic plug. Starks' Knob, Schuylerville, N.Y. Great horizontal shear zone near base of quarry on southeast side of plug. September 1, 1910. H.P.C.
371. .6 Volcanic plug. Stark's Knob, Schuylerville, N.Y. From east before opening.

DYKES

373. .1 Large dyke and smaller ones in foreground. West Spanish Peaks, from the northwest. New Mexico.
373. .2 Distant view of great dyke. East Spanish Peak from the northwest. N. Mex.
373. .3 Dyke 100 feet high. Near view of great dyke north of West Spanish Peak, New Mexico. From the northwest.
373. .4 Dyke. Devil's Slide, Utah. Transferred to 473. .4
373. .5 Dykes near Hoodoo Mountain, Yellowstone Park, Wyo.
373. .6 Worn out dyke; Pigeon Cove, Cape Ann, Mass. (9th Annual.)

SILLS

375. .1 Intrusive sill, Newark Series, Palisades, Hudson River, New Jersey.
375. .2 Triassic trap sheet dipping to left (south). Mt. Tom Range from Holyoke, Massachusetts.
375. .3 Trap flow on sandstone; Newark Series, City Quarry, Hartford Conn. 18th Annual; part 3.
375. .4 Upper surface of lower lava flow; is vesicular flow above solid Newark Series. Lane's Quarry, Meriden, Conn. 18th Ann, Part 3.

LACCOLITHS

377. .1 Dome shape due to buried laccolite. Green Mt., Wyoming.
377. .2 Diagram of laccolith. Black Hills district, South Dakota.

BATHYLITHS

379. .1 Granite cutting amphibolite; glaciated surface; Animas Canyon, Wyo.
379. .2 Amphibolite inclusions in Pre-Cambrain bathylith; Needle Mts. Colo.
379. .3 Greenville green schist intricately cut by granite; both lit-par-lit and mosaic types. Near St. Lawerence, Foster's Landing, N. Y. (Jefferson County)
379. .4 Algomian granite, (Middle Huronian) with Lower Huronian schist inclusions. Crane Lake, Northern Minnesota.

BREWSTER COUNTY, TEXAS

381.A.1 Volcanic tuff beds, a dyke in immediate foreground; 2 mile distant and right of center, a plug on center of mile-long dyke. Alamo Creek, 35 mile south Alpine, Brewster County, Texas.
381.A.2 Sill in limestone. Brewster County, Texas.
381.A.3 Sill in limestone with included block of limestone. Cedar Creek, 9 pt. Mesa sheet, Brewster County, Texas.
381.A.4 Sill in limestone, Cedar Creek, 9 pt. Mesa Sheet, Brewster County, Tex.
381.A.5 A laccolite with sharply upturned surrounding strata. Packsaddle Mt., Agua Fria sheet, 80 miles south Alpine, Brewster County, Texas
381.A.6 Laccolite, northeast corner Terlinga sheet, 80 miles south Alpine, Brewster County, Tex. Nos. and form a set. Gently arched beds over north end of laccolite.
381.A.7 Laccolite with inclined beds on east side dipping away from core, (shown in no. ) Beds are limestones with sills. 80 miles south of Alpine, Brewster County, Texas. Northeast corner of Terlinga, sheet.
381.A.8 Laccolite, northeast corner of Terlinga sheet. Center of sky-line igneous core, Cretaceous limestones overlying in three directions. Sharp peak on left another laccolite or plug. 80 miles south Alpine, Brewster County, Texas.
381.A.9 Laccolite on right, inclined Cretaceous limestone; on left Nos. and are in rough order left to right, of same laccolite. 1 mile southeast of Henderson Ranch, 9 pt. Mesa sheet, 70 miles south Alpine, Brewster County, Texas.
381.A.10 Henderson laccolite. View to right of No. . Center and left limestones over core, right, the core brought up by a fault. In distance the Rosillos Mountains, an enormous dissected laccolite. 70 miles south Alpine, Brewster County, Texas.
381.A.11 Upper surface of Henderson laccolite. Limestones on right resting on igneous core shown in left half. No. is view to right of this. 70 miles south Alpine, Brewster County, Texas.

IGNEOUS ROCKS. COMPOSITION

383. .1 Diagram to illustrate chemical variation of igneous rocks.
383. .2 Diagram showing chemical analyses of typical igneous rocks.
383. .3 Diagram to illustrate the varying proportions of the minerals of typical igneous rocks.