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Главная » 2013 » Ноябрь » 28
STRUCTURE
STRUCTURAL HIGHLIGHTS
The rocks in and south of Glacier National Park have been subjected to diastrophic forces at intervals from Precambrian time to the present. Most of the disturbances are reflected only in upwarps, which are so broad and gentle as to be inconspicuous but none the less significant in interpretation of the geologic history. In addition, but more locally, the rocks are intricately folded and broken by faults of several kinds and magnitudes. Igneous activity has left no recognized record since the close of the Precambrian era. The region is best known for its many overthrusts, which formed shortly after the close of the Mesozoic era. The largest, most widely known of these is the Lewis overthrust. This thrust did no
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STRATIGRAPHY (continued)http://www.nps.gov/history/history/online_books/geology/publications/pp/296/sec2-4.htm
CENOZOIC STRATA
The deposits of Cenozoic age in the part of Montana here described need more detailed study than they have yet received. As available data do not warrant use of formal formation names and require that unlike materials be mapped together in places, the map units chosen are based solely on characteristics readily recognizable in the field and will require modification when further work is done. The six units employed include old alluvium and associated deposits mapped in and west of the mountains described, remnants of deposits on the benches east of the mountains, two kinds of glacial deposits, modern alluvium, and landslide detritus. All are poorly consolidated or unconsolidated, and good exposures are rare except in stream bluffs and roadcuts. The probable range in age is from late Eocene to the present.
OLD ALLUVIUM AND ASSOCIATED DEP
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