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.

Middle Proterozoic Belt Supergroup, Western Montana part of MT Field Guides
From Great Falls, to Butte, Helena Glacier National Park and Spokane, this field trip crosses onto the leading edge of the Rocky Mountain thrust belt and proceeds to the stratiform copper-silver deposits in the Revett Formation of the Troy Mine in the main part of the Belt basin. The road log includes sections on the paleontology of the Middle Proterozoic Belt Supergroup, stromatolites of the Belt Supergroup (specific to Glacier National Park), Middle Proterozoic Tectonics of the Belt basin, and a sedimentologic and tectonic interpretation of the Belt Supergroup.

Heart Mountain Detachment Fault and Clastic Dikes of Fault Breccia, and Heart Mountain Break-Away Fault, Wyoming and Montana part of MT Field Guides
This field guide describes the geology of two sites near Silver Gate, MT (near Cooke City) where different features related to the Heart Mountain detachment are displayed. At the first site, several features pertaining to the origin of the Heart Mountain detachment fault can be examined, including: (1) severely deformed upper plate rocks in contact with undeformed lower plate rocks; (2) the character and composition of the fault breccia; (3) contacts of volcanic rocks with upper plate blocks and the Heart Mountain fault; and (4) dikes of carbonate fault-breccia injected into both upper plate blocks and overlying volcanic rocks. The second site is an exposure of the Heart Mountain break-away fault.

Crazy Mountains, Montana part of MT Field Guides
This trip examines a variety of mid-Eocene alkalic (feldspathoidal) stocks, laccoliths, sills, and dikes emplaced into Cretaceous and Paleozoic sedimentary strata. These rocks include mafic and felsic varieties, and are both texturally and compositionally variable. Most of the mafic alkalic rocks are unique in the Montana Alkalic Province in having Na2O > K2O. They are unusual even among feldspathoidal rocks because they are stongly enriched in incompatible elements, and have Sr, Nd, and Pb isotopic compositions which reflect an ancient source having low Rb/Sr, Sm/Nd, and U/Pb.

Field Guide to the Mountain View and West Fork Areas, Stillwater Complex, Montana part of MT Field Guides
The Mountain View area of the Stillwater Complex, which is exposed on the west side of the Stillwater River valley, contains a well exposed, easily accessible section through the Ultramafic series. In this area the ultramafic cumulates have, for the most part, escaped the serpentinization common in other parts of the complex. The Basal series rocks and the lowermost ultramafic cumulates, however, have suffereed extensive alteration. The hornfels and the sill/dike complex are reasonably fresh and well exposed in the Verdigris Creek area, the site of intensive exploration for Cu/Ni sulfides. The Banded series rocks are well exposed along the mine road leading to the abandoned Mouat chromite mine, although only Lower Banded series cumulates are present in this area.

Geology Along Going-To-The-Sun Road, Glacier National Park, Montana part of MT Field Guides
This guide to the geology along Going-to-the-Sun Road in Glacier National Park describes many of the major geologic features of the Park. It is directed toward the Park visitor with little no no background in geology. The guide begins with a short introduction to the science of geology and the geologic time scale, followed by a simplified geologic cross section through the Park from SW to NE. The bulk of the field guide is a 21-stop road log, keyed to numered octagonal signs along the road, which describes the geology along the road. A glossary of geologic terms and an appendix is included which contains a brief geologic history of Glacier National Park, explanations of rock colors and fossil algae (stromatolites), and descriptions of the Proterozoic rock formations that can be seen along the Going-to-the-Sun Road. An extremely useful resource included at the back of the book is a fold-out geologic map, plotted on an oblique shaded-relief diagram, that depicts the landscape and the distribution of rock formations and faults in the vicinity of Going-to-the-Sun Road.

Field Guide; Little Rocky Mountains part of MT Field Guides
This fieldtrip examines deformed Paleozoic sedimentary rocks on the margins of the Little Rocky Mountains, Tertiary intrusive rocks (porphyrys, magmatic-hydrothermal breccias, and dikes), and associated mineralization.

Geology of the Butte Mining District part of MT Field Guides
The Butte mining district is one of the major mining districts of the world with continuous production from both underground and open pit mines for 119 years, from 1864 to 1983. During this time, mining activites at Butte have introduced many firsts in mining methods, techniques of mine mapping, and the detailed recording of geologic data. This field guide describes the geology of the mineral deposits, provides a geologic map of the district, and concludes with a tour of eight locations of interest, including Alice pit, Syndicate pit, Berkeley pit, the Emma and Orphan Boy veins of the Anaconda system, the World Museum of Mining, and the Montana Tech Mineral Museum.

The Stillwater Complex, Southern Montana; A Layered Mafic Intrusion part of MT Field Guides
Layered complexes provide the most visible evidence of processes of magmatic differentiation; thus, they occupy a central place in the study of igneous petrology. Such complexes are not only scientifically rewarding, they are host to several types of mineral deposits, including copper-nickel, chromium, and platinum-group elements. The Stillwater Complex is one of the world's great layered mafic intrusions, distinguished not so much by its size as by the fact that it is tilted on its side, and erosion has exposed the layering to ready access. This fieldguide presents a summary of the geology of the complex in the Benbow and Mountain View areas. The Benbow area offers easy access to a variety of rocks from the ultramafic series and chromite deposits but only limited exposures of features from the banded series. The Mountain View area offers easy access to most of the banded series and the platinum deposits.

Multiple Catastrophic Drainage of Glacial Lake Missoula, Montana part of MT Field Guides
This field guide describes two localities related to the history and drainage of Glacial Lake Missoula northwest of Missoula, Montana. The first site highlights spectacular erosional and depositional features that illustrate the effects of extremely large discharge related to the drainage of the lake. In a sense, the area is the world's most extravagant natural flume experiment. Features include bedrock basins (scoured by flood waters), large deltaic bars, and megaripples as large as 35 feet from crest to trough. The second site, a large roadcut along I-90, contains a record of at least 36 fillings of the lake, presumably during Pinedale(?) time, suggesting that drainage occurred many times. Another roadcut exposes a similar, but unstudied record of deposition in a higher terrace that probably formed during Bull Lake(?) time and may indicate an older history of lake formation and drainage.