The Montana-Yellowstone Geologic Field Guide Database
A Digital Resource for Integrating Field-Based Research, Teaching, and Learning
Integrating Research and Education > Montana-Yellowstone Geologic Field Guide Database > Search the Database

Search the Database

Use this page to search our collection of educationally-useful geologic field guides and road logs in Montana and Yellowstone. You may search the database by entering a keyword to search or choosing one of the listed terms for geologic topic, geographic location, or geologic province.


Help

Results 31 - 40 of 54 matches

Bones and Rocks of the Upper Cretaceous Two Medicine-Judith River Clastic Wedge Complex, Montana part of MT Field Guides
The purpose of this field trip is to provide an overview of the paleontologic, stratigraphic, and paleoenvironmental aspects of the Upper Cretaceous Two Medicine-Judith River clastic wedge in western Montana. Strata of the Two Medicine Formation yielded the first evidence of such dinosaur social behavior as nest construction and parental care, and have provided important information concerning the processes of bonebed formation in the fossil record. The correlative Judith River Formation in Montana has yielded an abundant and diverse dinosaur fossil record primarily preserved as transported and concentrated accumulations of vertebrate remains ("microsites"). The geology and paleontology of four fossil localities [Seven Mile Hill, Shield's Crossing, Willow Creek Anticline (Egg Mountain), and the Badger Creek/Two Medicine River confluence] are described, but precise details concerning the locations of the sites are not given in the field guide.

Topics: Fossils, Sedimentary rocks
Geographic Location: North-Central Montana
Geologic Province: Montana Plains

Early Proterozoic Geology of the Highland Mountains, Southwestern Montana, and Field Guide to the Basement Rocks that Compose the Highland Mountain Gneiss Dome part of MT Field Guides
The Highland Mountains are underlain by the largest of the northwesternmost exposures of basement crystalline rocks in southwestern Montana....Metasedimentary rocks in the Highland Mountains are in part lithologically similar to the Late Archean multilithologic sequence (in the Tobacco Root, Ruby, and the northern Madison and Gravelly Ranges), but are considerably thinner. In the Highland Mountains the individual beds of aluminous schist, marble, quartzite, and iron-formation extend for only short distances, but the assemblage as a whole is mappable. It nowhere exceeds 300 ft (100 m) in thickness and appears to pinch out to the north....these rocks in the Highlands, unlike those to the southeast, are overlain by more than 10,000 ft (3000 m) of aluminous biotite gneiss that may have been deposited as muds basinward from the Late Archean shelf edge.

Geographic Location: Southwest Montana
Geologic Province: Central Rocky Mountains Foreland Province

Geology of the Highwood Mountains, Montana: A Survey of Magma Types and Sources part of MT Field Guides
The Highwood Mountains represent a dissected Eocene volcanic and intrusive complex composed of latites and highly potassic, mafic to felsic igneous rocks. Along with the Bearpaw Mountains and Eagle Buttes, they form a northeast-trending belt within the Montana Alkalic Province, and were all emplaced between 54 and 50 Ma. In the Highwoods an older suite of quartz-normative latites is overlain and intruded by a younger suite composed mostly of mafic phonolite flows and dikes, minette and trachyte dikes, and shonkinite-mafic syenite stocks. This trip examines a variety of dikes, sills, and stocks composed of these unusual rock types.

Topics: Metamorphic rocks, Igneous rocks, Sedimentary rocks
Geographic Location: North-Central Montana
Geologic Province: Montana Plains

Shonkin Sag and Square Butte Laccoliths, Montana part of MT Field Guides
Shonkin Sag and Square Butte laccoliths are at the eastern edge of the Highwood Mountains as part of the Central Montana Alkalic Province. Rocks in the Highwood Mountains date to 50-53 Ma. Both laccoliths are internally differentiated and contain a variety of rock types, including shonkinite, syenite, and pegmatite.

Topics: Sedimentary rocks, Igneous rocks
Geographic Location: North-Central Montana
Geologic Province: Montana Plains

Bearpaw Mountains, Montana part of MT Field Guides
This trip examines volcanic and shallow intrusive rocks in the Bearpaw Mountains which were emplaced during the period from about 54 to 50 Ma, in the late early Eocene and early middle Eocene. Within this area, wwo volcanic fields lie north and south of a central anticlinal arch in which uppermost Paleozoic and Upper Cretaceous sedimentary rocks and many intrusions are now exposed. The trip follows a route across the northern volcanic field into the core of the central arch to examine the variety of rock types in the Rocky Boy stock and the youngest volcanic rocks on Centennial Mountain (Chippewa Cree Tribe). Land traversed is on Hill County park land and private land; permission is required for access and collection of samples.

Topics: Structures, Sedimentary rocks, Igneous rocks
Geographic Location: North-Central Montana
Geologic Province: Montana Plains

Missouri Breaks Diatremes, Montana part of MT Field Guides
The Missouri Breaks diatremes are some of the best exposed diatremes in the United States, and display remarkable subsidence features. The diatremes and associated intrusions are important in showing (1) genetic connections of alnoitic, kimberlitic, and carbonatitic magmas, (2) xenolith suites representing the upper mantle and lower, middle, and upper crust of the Eocene lithosphere, and (3) mechanisms of eruption and emplacement of volatile-rich magmas. Some of the diatremes are fairly accessible in good weather. However, the Missouri Breaks is a remote area in which most of the roads are unimproved tracks across clay-rich sedimentary rocks, and even a small amount of rain may immobile four-wheel drive vehicles and make steep grades terminally hazardous.

Topics: Sedimentary rocks, Igneous rocks, Metamorphic rocks
Geographic Location: North-Central Montana
Geologic Province: Montana Plains

Smoky Butte Lamproite, Montana part of MT Field Guides
Smoky Butte is a composite pluglike mass, one of several in a 3-km-long zone of dikes and plugs of lamproite. K-Ar age is 27 +/- 3 Ma on phlogopite in a sample from the quarry on Smoky Butte and is the youngest igneous age in eastern Montana. The wall rocks are the Tullock Member of the Paleocene Fort Union Formation, immediately above the Tertiary-Cretaceous boundary. Dikes are discontinuous and show en echelon offsets probably related to intrusion mechanics rather than to faulting. Pockets of lamproite breccia and heterolithic breccia, containing vesicular lamproite fragments (locally pumaceous) and slightly metamorphosed fragments of Fort Union rocks, occur along the dikes and make up part or all of some of the irregular igneous bodies along the zone. Some dike margins show ropy pahoehoelike texture. Welded agglutinates are locally interlayered with bedded tuffs and occur as blocks wtihin some of the heterolithic breccia bodies.

Topics: Metamorphic rocks, Igneous rocks, Sedimentary rocks
Geographic Location: North-Central Montana
Geologic Province: Montana Plains

Great Falls to Wolf Creek (Via I-15) part of MT Field Guides
Great Falls is underlain by the Lower Cretaceous Kootenai Formation (Aptian), a series of red sandstones and shales which is considered to have been deposited in a "mostly" nonmarine environment. The city is on a crest of a broad northwest-plunging anticline called the South Arch, which lies just east of the Montana Thrust Belt. As we drive southwestward towards the Montanta Thrust Belt today, we will travel off the northwest flank of the South Arch. This will take us gradually from Lower Cretaceous to Upper Cretaceous outcrops until we reach the edge of the mountain front.

Topics: Structures, Igneous rocks, Sedimentary rocks
Geographic Location: North-Central Montana
Geologic Province: Montana Plains, Central Rocky Mountains Foreland Province, Rocky Mountain Fold-Thrust Belt

Rhyolite-Basalt Volcanism of the Yellowstone Plateau and Hydrothermal Activity of Yellowstone National Park, Wyoming part of MT Field Guides
This field guide provides an overview of the major geologic and hydrothermal features along the park roads through the western and northern parts of Yellowstone National Park. A number of sites from Old Faithful to Mammoth Hot Springs are described in the context of the geologic history of the Yellowstone region. Areas receiving special emphasis are the Firehole River and Upper Geyser Basin (including the Old Faithful area), Midway and Lower Geyser Basins, Firehole Canyon, Madison Junction, Norris Geyser Basin, the Norris-Mammoth Corridor, and Mammoth Hot Springs.

Topics: Surficial geology, Structures, Hydrology, Igneous rocks, Sedimentary rocks
Geographic Location: Yellowstone National Park
Geologic Province: Yellowstone Plateau

Geology and Evolution of the Grand Canyon of the Yellowstone, Yellowstone National Park, Wyoming part of MT Field Guides
This field guide concerns that part of the Grand Canyon of the Yellowstone seen by most visitors between Chittenden Bridge and Sevenmile Hole. The focus of the field guide is the stratigraphy and erosional history of the volcanic and sedimentary rocks (all younger than 610 Ka) that are observed in the canyon walls at 11 locations within or adjacent to the canyon: Inspiration Point, Red Rock, Lower and Upper Falls, Cascade Creek, Uncle Toms Trail, Uncle Toms Rest Area, Artist Point, and a location near Chittenden Bridge. The volcanic and sedimentary features observed at the various stops are discussed in terms of a sequential geologic framework.

Topics: Surficial geology, Igneous rocks, Sedimentary rocks
Geographic Location: Yellowstone National Park
Geologic Province: Yellowstone Plateau