Abstract This field guide describes a three-day trip from Vancouver, British Columbia, to the Wells Gray–Clearwater volcanic field (WGCVF) in east-central British Columbia. The WGCVF is the site of transitional to alkali olivine basaltic volcanism erupted over the last three million years. The small volume magmas (<1 km 3 ) erupted along preexisting normal faults related to the late stages of Cordilleran terrane amalgamation, along the boundary between the miogeoclinal and pericratonic rocks of the Kootenay terrane and the allochthonous Slide Mountain and Quesnellia terranes west of ancestral North America. The magmas are highly enriched in incompatible elements, especially large-ion lithophile elements, and are interpreted as the result of low degrees of partial melting of a heterogeneous, metasomatized mantle. Upon ascent through the crust, they carried up both crustal and mantle xenoliths. During the eruptive period of the WGCVF, at least four glacial periods have occurred. The interplay between volcanism and glaciation is captured in the wide range of volcanic features found in the region. Field trip participants will view numerous diverse volcanic landforms and deposits: from tuyas to ice-marginal valley-edge deposits, volcanoclastic-lacustrine deposits, and associated pillow lavas and hyaloclastites.

Impact-generated lunar highland rocks have high Ir and other noble metal concentrations. This Ir enrichment is produced by the admixture of a small amount of an undifferentiated meteoritic component. Similar high Ir concentrations are found in rocks from several large terrestrial impact craters. A compilation of all Ir analyses of terrestrial crater samples shows that there are now nine craters with a significant Ir anomaly (Ir > 1 ppb). Judging from the relative abundances of siderophile elements and the simultaneous enrichment of Cr, four of these craters were produced by chondritic projectiles. The Clearwater East impact melt, with an 8% chondritic component, is a well-characterized example. There is some evidence for achondrites, stony-irons, and iron meteorites being among projectiles of terrestrial impact craters. When present at any given impact site, Ir enrichment is commonly found in melt rocks and tends to occur in all samples from the same melt sheet. Lack of a meteoritic component may be due to a differentiated projectile, low in Ir and/or a high impact velocity. The excellent correlations among all siderophile elements and Cr in 23 samples from the Cretaceous/Tertiary boundary layer at Stevns Klint indicate that all these elements are contained in one component. The chondrite-normalized patterns are distinctly “terrestrial” in having large differences in concentrations of elements with similar cosmo-chemical volatilities, such as Au and Ge (low) and As and Cu (high), and suggest that the Ir-rich component is a mixture of meteorite and ejecta material from the site of the impact. However, it can be shown that a two-component mixture with various types of meteorites and terrestrial rocks cannot explain the observed element pattern. Some fractionation (e.g., volatilization and recondensation) may have modified the original pattern, making it difficult to identify the meteorite and, therefore, introducing large uncertainties on the fraction of meteorite in a given sample from a C/T boundary layer.

As humans venture back to the Moon, or onward to near-Earth objects and Mars, it is expected that the rigors of this exploration will far exceed those of Apollo . Terrestrial analogs can play a key role in our preparations for these complex voyages, since in addition to their scientific value, analogs afford the exploration community a means to safely prepare and test exploration strategies for future robotic and human planetary missions. Many relevant analog studies exist, and each is focused on a particular aspect of strategic development. Some analog programs such as the Pavilion Lake Research Project (PLRP) present the opportunity to investigate both real scientific and real exploration scenarios in tandem. The activities of this research program demand the use of techniques, tools, and strategies for underwater scientific exploration, and the challenges associated with the scientific exploration of Pavilion Lake are analogous to those human explorers will encounter on other planetary and small solar system bodies. The goal of this paper is to provide a historical synopsis of the PLRP's objectives, milestones, and contributions to both the scientific and exploration community. Here, we focus on detailing the development and deployment of an integrated science and exploration program with analog application to our understanding of early Earth systems and the preparation for future human space exploration. Over a decade of exploration and discovery is chronicled herein.

INTRODUCTION This paper presents the results of studies of the geology and fossil faunas of the Mingan Islands, Quebec, Canada. The writer first visited these islands in the summer of 1909 and spent seven days studying the sections of Parroquet, Mingan (Bald), Harbour, Moutange (Montange, Big Romaine), Moniac (Little Romaine, Montac), Quarry, Niapisca (Phantom), and Large islands. 1 Later, on August 31 and September 1 of that year, the sections of Eskimo Island and Clearwater Point were studied. The islands were again visited in July 1925, and the sections on Harbour, Inner Birch, Outer Birch, and Eskimo islands, and on Pte. aux Morts and Clearwater Point were studied or re-studied. A hurried reconnaissance was made of St. Charles, Ste. Geneviève, Whale, and Hunting (Betchewan) islands. The strata on these islands were identified as to formation, but weather conditions did not permit detailed study. The islands were again visited in 1929, and the sections on Harbour, Quarry, Niapisca, and Eskimo islands were re-studied. About a week was spent on Large Island and another week on Betchewan Bay. Sections on Hunting (Betchewan), St. Charles, and Ste. Geneviève islands were measured as were those on Pillage Bay, Betchewan Bay to Trilobite Bay, on Ammonite and Clearwater points, and in the bay on the west side of Clearwater Point. The section on Pte. aux Morts was studied in detail, and the shore east from Indian Point on the east side of Pillage Bay and that from Mingan Village to Magpie were examined. There are no . . .

Abstract This field guide covers geology across north-central Idaho from the Snake River in the west across the Bitterroot Mountains to the east to near Missoula, Montana. The regional geology includes a much-modified Mesozoic accretionary boundary along the western side of Idaho across which allochthonous Permian to Cretaceous arc complexes of the Blue Mountains province to the west are juxtaposed against autochthonous Mesoproterozoic and Neoproterozoic North American metasedimentary assemblages intruded by Cretaceous and Paleogene plutons to the east. The accretionary boundary turns sharply near Orofino, Idaho, from north-trending in the south to west-trending, forming the Syringa embayment, then disappears westward under Miocene cover rocks of the Columbia River Basalt Group. The Coolwater culmination east of the Syringa embayment exposes allochthonous rocks well east of an ideal steep suture. North and east of it is the Bitterroot lobe of the Idaho batholith, which intruded Precambrian continental crust in the Cretaceous and Paleocene to form one of the classical North American Cordilleran batholiths. Eocene Challis plutons, products of the Tertiary western U.S. ignimbrite flare-up, intrude those batholith rocks. This guide describes the geology in three separate road logs: (1) The Wallowa terrane of the Blue Mountains province from White Bird, Idaho, west into Hells Canyon and faults that complicate the story; (2) the Mesozoic accretionary boundary from White Bird to the South Fork Clearwater River east of Grangeville and then north to Kooskia, Idaho; and (3) the bend in the accretionary boundary, the Coolwater culmination, and the Bitterroot lobe of the Idaho batholith along Highway 12 east from near Lewiston, Idaho, to Lolo, Montana.