Igneous
Christine Falls and Tatoosh granodiorite, Mount Rainier NationalChristine Falls cuts a narrow slot through Tatoosh granodiorite, Mount Rainier National Park
Hand Samples of Intrusive igneous RocksFrom left to right, these rocks are arranged in order of decreasing silica content: granite, diorite, and gabbro.
Hand Samples of Volcanic RocksFrom left to right, these rocks are arranged in order of decreasing silica content: rhyolite, andesite, and basalt.
Granite and Moon. Sierra Nevada, CA.A typical exposure of granite --coarse grained with an interlocking, random assortment of crystals.
Mt. Whitney and Sierra Nevada, California at sunrise.Mt. Whitney and Sierra Nevada, California at sunrise. Mt. Whitney's elevation is 14, 505' above sea level, the highest spot in the conterminous US. The rock in this photograph is almost entirely granodiorite.
Intrusive contactCretaceous granite intruding Cambrian sedimentary rock, Sierra Nevada Range.
Granite sill intruding gneiss, Colorado.
Ig-08pegmatite dike and sill intruding mylonitic gneiss
Mt. Whitney Cretaceous GranodioriteAt an elevation of 14,505, Mt. Whitney reaches the highest peak in the conterminous United States, and like much of the Sierra Nevada, it consists of Cretaceous granodiorite, a rock intermediate in composition between granite and diorite. (Image ID # Ig-01
Cretaceous granodiorite, Yosemite NP, CA.
Granitic rock and moon. Sierra Nevada, CA.
Intrusive contact: granitic rock and metasedimentary rock in roo
Triassic metavolcanic rock of the southern Sierra Nevada.Cretaceous granodiorite can be seen intruding Triassic metavolcanic rock of the southern Sierra Nevada. The volcanic rock was contact metamorphosed by the intruding granite
(Image ID# Ig-06)
(Image ID# Ig-06)
Intrusive contact: granitic rock and metasedimentary rock in roo
Pegmatite intruding basement gneiss , CaliforniaNote how irregular the contact is between the two, and the small sill of pegmatite intruding along foliation in the gneiss. (Image ID # Ig-08)
Road covered by recent lava flow, Hawaii.
Granitic dike intruding gneiss, Teton Range, WY.
Ig-102
mafic dike intruding gneiss. Note fault.
Ig-101
Pahoehoe lava, Hawaii.
Pillow basalt, Lopez Island, WA.
Phreatic explosion craters. Little Hebe Craters, Death Valley,
Metamorphosed pillow basalt (Purcell Lavas--greenstone), Glacier
Ig-12
Phreatic explosion craters. Ubehebe Crater, Death Valley, CA.
Mafic dike intruding sedimentary rock, SE Cal.
Apophyses of granitic rock intruding gneiss, NV.
Ig-17
Dioritic inclusions in granitic dike intruding slate, southern B
Phreatic explosion craters. Little Hebe Craters, Death Valley,
Aplite dike in granite.
Ig-18
sills of pegmatite in gneiss.
Diabase sill in marble, southern Death Valley, CA.
Diorite sill (Purcell sill) intruding Precambrian Belt Supergrou
Granite sill intruding gneiss, Colorado.
Diabase sills (green) in limestone, SE Cal.
pegmatite sill in gneiss.
Ig-26
Granodiorite.
Cross-cutting relations: 1st the mafic inclusion; 2nd the granod
Garnet Peridotite
Pegmatite veins in diorite.
Pegmatite sill and gneiss, Colorado.
Pegmatite dike, Teton Range, WY.
Pegmatite dike intruding gneiss, Colorado.
Slate inclusions in granite, Wasatch Mtns., Utah.
Mt. Rainier, WA.
Stratified cumulate minerals, Stillwater Complex, MT. Dark laye
Mt. Rainier, WA.
Sill intruding Dolomite of the Helena Formation, Glacier National Park, MontanaThe dark band in this cliff face is the Purcell Sill, and diorite sill that intrudes rock of the Proterozoic Belt Supergroup in Glacier National Park. The white rock on either side of the sill is bleached because of the contact metamorphism. (Image ID# lg-25)
Mt. Rainier and Seattle, WA.
Ig-39
Mt. Hood, OR. View North to Mt. Rainier, WA.
Crater and dome of Mt. St. Helens, WA.
Ig-46
Ig-47
Geologists in crater of Mt. St. Helens, WA
Rhyolitic Obsidian Flow, Newberry Volcano, OR.
Cascade Volcanoes, OR.
Mt. Shasta, CA.
Ig-51
Caldera and cinder cone: Crater Lake and Wizard Island, OR
Lassen Peak, CA.
Obsidian.
Obsidian flow and South Sister volcano, OR.
Caldera. Long Valley caldera, CA.
Crater and dome of Mt. St. Helens, WA.
Caldera and cinder cone: Crater Lake and Wizard Island, OR
Tertiary tuff at Smith Rocks State Park, OR.
Bandelier Tuff, New Mexico.
Welded tuff and vitrophyre, SE Cal.
Pumice deposit, Idaho
Plug dome and Mono Lake, CA.
Lahar deposit, SE Cal.
Ig-65
Tilted ash deposit, SE Cal.
Lahar deposit, S. Colorado.
Basalt overylying rhyolite at Twin Falls, Idaho.
Flow-banded rhyolite.
Yellowstone ash deposit in SE Cal.
Welded tuff.
Lithophysae in obsidian.
Porphyritic andesite.
Pyroclastic rock.
Volcanic neck: Agathala Peak, Arizona.
Pumice floating in water.
Rhyolite flow, Yellowstone NP.
Basalt flow, northern BC Canada. Note that it shows the upper a
Recently erupted basalt on Snake River Plain, Idaho.
Aa and pahoehoe lava, Idaho.
Columbia River and Columbia River Basalts, OR-WA. Washington on
Ig-84
Ig-85
Cross-section of basaltic columns, Devil's Postpile NM, CA. Gro
Collapsed lava tube and cinder cones on shield volcano: Medicine
Pahoehoe and Pele's Hair, Hawaii.
Ig-88
Cinder cones and aa flow, N. California.
NE rift of Mauna Loa volcano, Hawaii.
Columnar jointing in basalt flow, WA.
Cinder cone and flow, Mauna Loa, Hawaii.
Cinder cone and flow, Lassen NP, Cal.
Erupting cinder cone: Pu u Oo, Hawaii.
Ig-94
Ig-98
Pahoehoe lava, Hawaii.
Paleosol at base of basalt flow, Idaho.
Pahoehoe lava, Hawaii.
Vertical cut through cinder cone, SE California.
