Clearwater Mountains Research Articles

Orogen-scale inverted metamorphism during Cretaceous–Paleogene terminal suturing along the North American Cordillera, Alaska, USA

Abstract The northern North American Cordilleran margin has been active for >200 million years, as recorded by punctuated phases of crustal growth and deformation. Accretion of the exotic Wrangellia Composite Terrane (Insular Belt) is considered the largest addition of juvenile crust to the Cordilleran margin, though margin-parallel translation during the Cenozoic has obscured much of the accretionary history. Three zones of inverted metamorphism spatially correspond to the Insular–North American suture zone from north to south: (1) Clearwater Mountains; (2) Kluane Lake; and (3) Coast Mountains, each preserving kinematics indicative of thrusting of North American–derived rocks over Insular-derived assemblages. We performed in situ monazite petrochronology on samples collected across strike in both the Clearwater and Coast Mountain regions. New and recently published data from these three metamorphic belts indicate that thrust-sense deformation accompanied the formation of inverted metamorphic isograds from 72 to 56 Ma. We leverage recent estimates of Denali fault offset to reconstruct a >1000-km-long zone of inverted metamorphism and interpret it as the Insular–North America terminal suture.

Two new species of Pterostichus Bonelli subgenus Pseudoferonina Ball (Coleoptera, Carabidae, Pterostichini) from the mountains of central Idaho, U.S.A.

Two new species of Pterostichus Bonelli subgenus Pseudoferonina Ball, are described from the mountains of central Idaho: Pterostichus bousqueti Bergdahl [type locality = small tributaries of South Fork of Payette River watershed, ca. 1170 m (3840 ft), 44.0675°; -115.6822°, near Lowman, Salmon River Mountains, Boise County, Idaho, U.S.A.] and Pterostichus lolo Bergdahl [type locality = Cottonwood/Orogrande Creek, ca. 870 m (2850 ft), 46.5528°; -115.5522°, North Fork of Clearwater River watershed, Clearwater Mountains, near Bungalow, Clearwater County, Idaho, U.S.A.]. Males of Pterostichus bousqueti and Pterostichus lolo are easily distinguished from each other and the seven previously described Pseudoferonina species by the form of the median lobe of the aedeagus, and from most individuals of the other species of Pseudoferonina in Idaho by features of pronotal shape and macrosculpture. Both species appear to be obligate ripicolous hygrophiles, restricted in distribution primarily to the margins of small montane streams in forested areas. Widespread intensive stream surveys for Pseudoferonina over many years indicate the geographic ranges of both species are highly localized, and additional undescribed species may occur in Idaho.

Bryophytes of the Tenmile Creek Drainage, Idaho

A collection of 221 bryophyte taxa from the Tenmile Creek drainage, Idaho County, Idaho, includes 22 species and two varieties that are new reports for the state. The Tenmile Creek drainage contributes to the South Fork of the Clearwater River in the Clearwater Mountains of central Idaho. With roughly equal portions lying in Nezperce National Forest and the Gospel-Hump Wilderness Area, the drainage is approximately 135 km2 and 1067-2725 m in elevation. The rugged topography of the drainage offers a diversity of environmental gradients relating to elevation, moisture and exposure. It is principally the product of the fluvial erosion during the Sangamon interglacial of this local portion of the extensive, acidic igneous Idaho batholith (Ross & Forrester 1958). Most of the drainage is forested (timberline is ca. 2560 m) and, based on Daubenmire (1952) and Steele et al. (1976), three forest types-douglas fir forest (xeric sites, lower elevations), grand fir forest (mesic sites, lower to middle elevations) and subalpine fir forest (mesic sites, middle to upper elevations)-can be recognized. The majority of the study area's bryophyte taxa appears to be either restricted to or principally distributed within a single forest type. Some of the more frequently encountered of such taxa include: (1) douglas fir forest-Encalypta ciliata, Grimmia calyptrata and Orthotrichum rupestre; (2) grand fir forest-Bartramia pomiformis, Claopodium bolan- deri, Dicranum tauricum, Heterocladium procurrens, Hylocomium splendens, Scleropo- dium obtusifolium, Lophozia kunzeana, Plagiochila porelloides, Radula complanata and Scapania umbrosa; (3) subalpine fir forest-Brachythecium collinum, Dichodontium olym- picum, Hygrohypnum molle, Kiaeria starkei, Mnium blytii, Pohlia cruda, Polytrichastrum lyallii, Rhacomitrium sudeticum f. alpinum, Tortula norvegica, Cephalozia bicuspidata and Lophozia wenzelii. Bryophyte collections from above the timberline were made only at the summit of Buffalo Hump, the highest point within the study area. Four of the 15 bryophyte taxa collected at this rocky and barren site-Encalypta rhaptocarpa, Hypnum revolutum, Mnium arizonicum and Pohlia obtusifolia-were found nowhere else within the study area. Beginning at about the latitude of the study area and extending to the north in the Rockies, a number of otherwise more coastally distributed subalpine vascular plant species such as Thuja plicata, Pinus albicaulis and P. monticola appear in the Rocky Mountain flora. This floristic intrusion is attributed to westerly winds that carry an oceanic climatic influence well inland at these latitudes. Such a floristic intrusion has also been noted among bryophytes (Schofield 1965; Ahti & Fagersten 1967). Three of the taxa here reported as new to the state-Cynodontium jenneri, Rhacomitrium heterostichum var. occidentale and Stokesiella praelonga var. praelonga-have been previously reported only from more coastal localities. The bryoflora consists of 152 species of mosses and 55 species of liverworts. Twenty-

Relationships between Overstory Structure and Understory Production in the Grand Fir/Myrtle Boxwood Habitat Type of Northcentral Idaho

Relationships between Overstory Structure and Understory Production in the Grand Fir/Myrtle Boxwood Habitat Type of Northcentral Idaho

Homing of Transplanted Alaskan Brown Bears

Homing of Transplanted Alaskan Brown Bears

Changes in elevation of the Rocky Mountains in Pleistocene time as possible climatic factors

It is well known that the Sierra Nevada and Cascade ranges intercept, moisture from the Pacific, causing it to be precipitated on their western slopes with resulting arid or semi‐arid conditions east of them. In a less degree the Rocky Mountains effect a similar result, particularly north of the latitude of Yellowstone Park. Precipitation on their western sides or westernmost ranges, such as the Clearwater Mountains, Cœr d'Alene, Cabinet, and Purcell ranges is much greater than on the ranges farther east or the plains beyond. It follows that if the intercepting ranges were removed or even lowered considerably, the interior plateaus and the great plains in northern United States and Canada would receive an increased precipitation which, of course, would be one of the factors necessary to renewed glaciation. In this connection, it is noteworthy, perhaps, that in the Olympic Mountains, which receive a heavy precipitation, permanent snow and ice‐fields are rather general above an altitude of five thousand feet. Farther east in the same latitude, the present lower ice‐limit rises as the precipitation decreases. In Glacier Park it is at least seven thousand feet.

Summaries of Recent North American Pre-Cambrian LiteratureThe Structure of the Piedmont Plateau as Shown in Maryland. Edward B. MathewsGenesis of the Amphibole Schists and Serpentines of Manhattan Island, New York. A. A. JulienGranites of North Carolina. T. L. WatsonThe Geological Structure of the Southwestern New England Region. William H. HobbsLineaments of the Atlantic Border Region.A Treatise on Metamorphism. Charles R.

Previous articleNext article FreeReviewsSummaries of Recent North American Pre-Cambrian Literature The Structure of the Piedmont Plateau as Shown in Maryland. Edward B. Mathews Genesis of the Amphibole Schists and Serpentines of Manhattan Island, New York. A. A. Julien Granites of North Carolina. T. L. Watson The Geological Structure of the Southwestern New England Region. William H. Hobbs Lineaments of the Atlantic Border Region. A Treatise on Metamorphism. Charles R. Van Hise The Menominee Iron-Bearing District of Michigan. W. S. Bayley The Menominee Special Folio. Charles R. Van Hise , W. S. Bayley The Baraboo Iron-Bearing District of Wisconsin. S. Weidman Economic Resources of Moose River Basin. James M. Bell The Abitibi Region. George F. Kay The Classification of the Archean. A. P. Coleman The Contact of the Archean and Post-Archean in the Region of the Great Lakes. A. B. Willmott The Northern Nickel Range. A. P. Coleman Report on an Exploration of the East Coast of Hudson Bay. A. P. Low The Newly Discovered Rock at Sioux Falls, South Dakota. J. E. Todd Quarrying Industry of Missouri. E. R. Buckley , H. A. Buehler Economic Resources of the Northern Black Hills. J. D. Irving Preliminary Report on the Geology of the Arbuckle and Wichita Mountains in Indian Territory and Oklahoma. Joseph A. Taff An Occurrence of Greenstone Schists in the San Juan Mountains, Colorado. Ernest Howe The Copper Deposits of the Encampment District, Wyoming. Arthur C. Spencer A Geological Reconnaissance Across the Bitterroot Range and Clearwater Mountains in Montana and Idaho. Waldemar Lindgren The Geology and Ore Deposits of the Bisbee Quadrangle. F. L. Ransome Geology of the Globe Copper District, Arizona. Description of the Globe Quadrangle. Description of the Bisbee Quadrangle. A Geological Reconnaissance Across the Bitterroot Range and Clear-water Mountains in Montana and Idaho. Waldemar Lindgren C. K. Leith, and W. D. S.C. K. Leith Search for more articles by this author , and W. D. S. Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Journal of Geology Volume 13, Number 2Feb. - Mar., 1905 Article DOIhttps://doi.org/10.1086/621215 Views: 47 PDF download Crossref reports no articles citing this article.