Ellipsoidal Lavas in the Glacier National Park, Montana

Burling, Lancaster D.

doi:10.1086/622325

Cited by 4 publications

(3 citation statements)

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“…L. D. Burling (1916) says the Purcell lava near Shepard Glacier is 150 feet thick and-"composed of 6 or more flows, each of uneven and more or less ropy surface, separated by small and more or less local accumulations of shale. The lower 25 or 30 feet of the flow is composed of a conglomeration of dense, homogenous, spheroidal masses averaging 1 to 2 feet in diameter.…”

Section: Purcell Basaltmentioning

confidence: 99%

Geology of Glacier National Park and the Flathead Region, Northwestern Montana

Ross¹

1959

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Page region_________________________________ 11 2. Altyn limestone in the lower slopes of Appekunny Mountain, northeast of Many Glacier Hotel, Glacier National Park______ 11 3. Air view northeast from above Gunsight Pass toward the valley of St. Mary River, with Lake Ellen Wilson in the foreground______ 26 4. Grinnell argillite on Broken Leg Mountain, Nyack quadrangle, Flathead region_______ 28 5.=Grinnell argillite on Broken Leg Mountain, Nyack quadrangle, Flathead region_______ 28 6. Photomicrographs of rocks of the Belt series__ 29 7. Molar-tooth structure in Siyeh limestone in roadcut along Going-to-the-Sun Highway, Glacier National Park___________________ 35 8. Irregular banding in Siyeh limestone in roadcut along Going-to-the-Sun Highway, Glacier National Park___________________ 35 9. Photomicrographs of rocks of the Belt series and associated igneous rocks_____________ 36 10. Conophyton in road cut in Siyeh limestone above the big switchback on Going-to-the-Sun Highway, Glacier National Park__________ a7 11. Stromatolite on Tongue Mountain, Nyack quadrangle, Flathead region______________ 37 12. Argillite of the Missoula group with sand-filled mud cracks, Upper Twin Creek, Marias Pass quadrangle, Flathead region_________ 46 13. Cusped ripple marks in argillite of the Missoula group, head of Grouse Creek, Marias Pass quadrangle, Flathead region__ 46 14. Clay spalls in argillite of the Missoula group below Mount Bradley, Marias Pass quadrangle, Flathead region__________________ 47 15. Laminated argillite of the Missoula group with a small stromatolite, in railroad cut nearly opposite the mouth of Coal Creek Nyack quadrangle, Flathead region_______ 47 16. View north from the head of Avalanche Basin, Glacier National Park___________________ 57 2 GEOLOGY OF GLACIER NATIONAL PARK AND THE FLATHEAD REGION, NORTHWESTERN MONT.The block above the Lewis overthrust was itself deformed but, in the part now remaining, much less intensively than the rocks below. Adjustments that may have begun during the overthrusting and continued to the present have fractured the overlying block.A series of geomorphic events not clearly recorded in the present topography reached a culmination in a mature surface (the Blackfoot surface) near the end of the Tertiary period. Several stages of glaciation with an intermediate stage in which rejuvenated stream erosion cut deep gorges have modified and, over large areas, obliterated the Blackfoot surface. Nevertheless, the present topography still reflects the structure of the underlying rocks. Since the close of the Pleistocene epoch, renewed erosion has caused the streams to cut small inner gorges in the valley floors. Also small glaciers reappeared in the uplands carved by the far larger Pleistocene ice streams, and some of these minor glaciers persist to the present day.

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Section: Purcell Basaltmentioning

confidence: 99%

Geology of Glacier National Park and the Flathead Region, Northwestern Montana

Ross¹

1959

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“…Their unpublished field notes and maps (located at the USGS Field Records, in Denver, Colorado) provide details of descriptions and localities for the Purcell Lava not included in subsequent publications. Burling (1916) drew attention to the ellipsoidal base (pillows) of the lowest lava flow at two localities within the Park and concluded that the entire sequence of lava flows was subaqueous in origin. However, he acknowledged that in other localities where the spheroidal masses were seemingly absent and the underlying argillites were ripple-marked and mudcracked, the flows could have been subaerial.…”

Section: Previous Workmentioning

confidence: 99%

“…Prior to this study, the Pur cell Lava in Glacier National Park was generally thought to have been extruded entirely within a subaqueous environment (Burling, 1916;Fenton and Fenton, 1937). This interpretation was based on the presence of pillow lava, steam tubes, what were thought to be primary sediment inclusions, banded amygdule fillings mistaken for sediment, olive-colored flowtops mistaken for intercalated sediment, and the fact that the lava flows occur within a thick succession of miogeosynclinal sedimentary strata.…”

Section: Environment Of Emplacementmentioning

confidence: 99%