Cumulate Xenoliths in the Lodgepole, Enos Mountain and Susie Peak Intrusions: A Guide part of MT Field Guides
The Lodgepole, Enos Mountain and Susie Peak plutons represent multiple intrusions of intermediate magma that were emplaced at depths ranging from near-surface to 2 km during the Late Cretaceous....These intrusions lie, respectively, 8, 9 and 12 km north of the nearest outcrops of the Stillwater Complex. The Lodgepole intrusion is composed of an early, dacitic phase and a later, dioritic phase; the diorite contains abundant xenoliths (maximum 31 cm diameter) in the area north of Clover Basin near its west margin. These xenoliths include foliated mafic amphibolite, gneiss, Paleozoic sedimentary rocks and mafic cumulates. Smaller xenoliths of similar rock types are found in the Enos Mountain and Susie Peak intrusions....Mineral compositions and textures lead to the conclusion that the cumulate xenoliths were brought up from a buried underlying extension of the Stillwater Complex.

Guide to the Picket Pin Mountain Area part of MT Field Guides
This traverse through part of the Banded series provides relatively easy access to the upper half of the exposed part of the Stillwater Complex. The percentage of outcrops is high, and even in areas of soil or tundra cover, the float appears to be sufficiently immobile and concentrated to give an accurate picture of the underlying bedrock geology....The traverse begins in the Middle gabbro zone and terminates where Paleozoic limestone unconformably overlies the Upper anorthosite zone. Above the Middle anorthosite zone, it follows the Picket Pin section described by McCallum and others (1980) and Raedeke (1982b)....An optional traverse through some lithologically complex and intriguing rocks in the Upper anorthosite zone north of the Castle Creek fault is also described. Total traverse time, including the drive from Carter's Camp and return, is 8-10 hours. Elevations range from 9,300 to 10,000 feet.

Guide to the Benbow Area part of MT Field Guides
The Benbow area (named for T.C. Benbow, who first discovered chromite there) is at the east end of the exposed Stillwater Complex....Most of the localities described...are in the Ultramafic series....The features emphasized at these localities include the nature of the cyclic units, pegmatoids associated with chromite seams, evidence for slumping anbd slope instability in the Stillwater magma chamber, lateral persistence of some of the chromite seams, and the unconformity between the Banded series of the Stillwater Complex and overlying Cambrian limestone.

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.

Field Guide to an Archean Transect, Eastern Beartooth Mountains, Montana-Wyoming part of MT Field Guides
The eastern Beartooth Mountains of Montana and Wyoming contain a record of crustal evolution that spans almost 1000 Ma and culminates in a major episode of crustal growth 2700-2800 Ma. The earlier record is sparse and complex as a result of extensive magmatism and intense metamorphism associated with Late Archean activity. In general, however, it appears that continental material was present in this area by roughly 3600 Ma, and that a stable continental shelf accumulated quartzites, iron-formation, and lesser amounts of pelitic to psammitic units interspersed with small volumes of mafic to silicic volcanic rocks. This cycle of accumulation was apparently terminated by an episode of granulite facies metamorphism 3300-3400 Ma, perhaps as a result of continent-continent collision....About 2800-2900 Ma, a second major cycle of crustal growth began that bears some resemblance to those associated with modern continent-ocean subduction zones....The first igneous rocks produced during this cycle were andesitic or dioritic rocks, both coarse and fine grained, that were subsequently metamorphosed to amphibolite facies....This interval is restricted by the presence of a granodioritic series (Long Lake granodiorite) that was intruded late in the kinematic cycle... (2779 Ma)...and marks the lower limit for the last major episode of regional metamorphism. The last and most volumetrically important rock produced during the cycle was the Long Lake granite. This unit composes approximately 80-90% of the eastern portion of the range and engulfs all older rock types. It appears to have been intruded about 2740 Ma....This excursion will attempt to view the evidence of these two major cycles in four main stops: (1) Hellroaring Plateau, (2) Lower Quad Creek, (3) Upper Quad Creek, and (4) Long Lake. Late Archean mafic dikes (at Beartooth Lake) will also be examined.

Field Guide; Belt Butte and Tiger Butte part of MT Field Guides
This field trip extends east from Great Falls across rolling glacial plains to the summit of Belt Butte, where its formation and the collapse structure adjacent to it will be discussed. In addition, the Tiger Butte laccolithic intrusion, contact metamorphic effects, associated dikes, and structure resulting from the intrusion will be examined.

Field Guide; North Moccasin and Judith Mountains part of MT Field Guides
The emphasis of this field trip is to examine gold mineralization hosted in karsts breccias at the Kendall mining district and the relationship between intrusives, Paleozoic sedimentary rocks and mineralization in the Judith Mountains.

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.

Field Guide; Bearpaw 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.

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.