The Scarface thrust of the western Madison Range, Montana, is a 17° west-dipping Late Cretaceous thrust that places Archean gneisses over a complexly folded panel of Phanerozoic sedimentary rocks. The Archean-Cambrian contact on the footwall of the Scarface thrust is nearly vertical, and both bedding in the cover and foliation in the gneisses near the contact were rotated by 38° during folding. Paleozoic rocks up section in the footwall are overturned, with an axial surface that dips less than 10° west. The Scarface thrust is locally folded over lower Paleozoic rocks on the footwall. Folding was produced by post-Scarface thrust movement on a minor east-dipping splay fault that follows bedding in Devonian rocks. Of the two dominant shear fracture and fault sets in the basement (strikes and dips of N52°W, 47°NE; N20°W, 50°SW), the northeast-dipping set is parallel to foliation and reflects a strong influence of foliation on basement deformation. Intergranular fractures nucleated at the tips of biotite grains. Narrow zones of cataclasis containing shredded biotite formed along the intergranular fractures. Advanced stages of deformation were accompanied by formation of thicker zones of wavy, foliated cataclasites defined by dark seams of comminuted biotite, feldspar, and quartz. The recumbent footwall syncline is superimposed on the west limb of a large, more open syncline in Paleozoic and Mesozoic rocks. We are unable to resolve which fold formed first. Faulting sequences are also equivocal. The Scarface thrust may have been emplaced as a shallowly dipping sheet, or it may have been steeper initially and rotated during movement on the structurally lower Beaver Creek thrust.

The Jakeys Fork fold and fault structure is a Precambrian granite-gneiss–cored anticline in the hanging wall of the steeply west dipping Ross Lakes shear zone. The Ross Lakes shear zone juxtaposes Precambrian rocks in its hanging wall and steeply dipping to overturned Cambrian and Ordovician sedimentary rocks in its footwall. Precambrian and Cambrian Flathead Sandstone in the hanging wall of the Ross Lakes shear zone are folded in an open, kinklike fold defined by gently and steeply dipping panels of Cambrian Flathead Sandstone. Precambrian rocks in the core of the hanging-wall anticline deformed by slip on a narrow fault in the hinge zone of the fold and by randomly oriented slip on narrow, discrete faults of many orientations on either side of the hinge zone. Cambrian Flathead Sandstone was welded to the Precambrian rocks during folding, and detachment occurred in the Cambrian Gros Ventre Formation. The Ross Lakes shear zone formed by brecciation and cataclasis. Precambrian rocks in the footwall of the Ross Lakes shear zone deformed by small amounts of slip on steeply west dipping faults, which resulted in a steepening of the contact between Precambrian rocks and the overlying Cambrian Flathead Sandstone. Faults in Precambrian rocks in the footwall of the Ross Lakes shear zone bound regions of undeformed Precambrian rock with widely spaced fracture sets. Cambrian Gros Ventre and younger formations are folded into a tight, overturned footwall syncline with its steep limb parallel to the Ross Lakes shear zone.

In contrast to results of regional soil radon studies in unglaciated areas, bedrock geology shows no correlation with radon concentrations in glacial soils overlying the Green Pond outlier and Reservoir fault zone, New Jersey Highlands. Total gamma radiation and uranium concentrations in the Paleozoic sedimentary rocks of the Green Pond outlier are generally lower than in the Precambrian gneisses of the Reading Prong to the west. The sedimentary bedrock shows average gamma radiation of 220 c/s (136 to 323 c/s) and uranium concentrations of 0.5 to 0.6 ppm, whereas gamma radiation from the Grenville gneisses averages 284 c/s (240 to 576 c/s) and average uranium concentrations are 1.2 to 2.2 ppm. Rare pegmatites that occur along the Reservoir fault zone yield anomalously high average gamma radiation of 2,018 c/s (1,949 to 3,495 c/s) and average uranium concentrations of 28.5 ppm. Radon concentrations in the glacial soil cover exhibited similar averages with wide ranges regardless of underlying bedrock geology. No appreciable difference was found between soil radon concentrations over Paleozoic sedimentary units, the pegmatites, fault zone, or Precambrian gneisses. Radon from soil over the Paleozoic sedimentary bedrock averaged 518 pCi/L (237 to 2,695 pCi/L), whereas it averaged 527 pCi/L (200 to 1,872 pCi/L) in soil over the Grenville gneisses. The Green Pond outlier and the Reservoir fault zone are blanketed by the Wisconsin-age glacial cover and contain recessional deposits that are proximal to the terminal moraine. All soil radon was sampled in the glacial cover. The glacial sediments contain erratics primarily composed of lithologies in the area but also of exotic rock types. Because uranium concentrations in the erratics and matrix are highly variable, soil radon of individual samples is governed by the local uranium concentrations. Other possible reasons for the lack of correlation between bedrock and soil radon are the high permeability of the glacial soil that permits radon diffusion, atmospheric dilution, and variations in cover thickness.