File:Central Connecticut in the geologic past (1915) (14764870784).jpg

Identifier: centralconnectic00barr (find matches)
Title: Central Connecticut in the geologic past
Year: 1915 (1910s)
Authors: Barrell, Joseph, 1869-
Subjects: Geology
Publisher: Hartford, Printed for the State Geological and Natural History Survey
Contributing Library: Wellesley College Library
Digitizing Sponsor: Boston Library Consortium Member Libraries

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an result, as the sedi-ment is more than sufficient to keep the basin filled. It is assumedin the structure section that a differentiation of the subsidingmargin of the basin from the rising rim so sharp as to requirethe development of a fault zone, had not yet arisen, though such aplane of weakness possibly may have been inherited from someearlier time and may have served as a plane of motion at thevery initiation of the Triassic basin. Close of the Appalachian Revolution, Figure p. — The pre-vious views have been based upon various lines of evidence whichgive a considerable knowledge of the character of the land sur-faces of the periods involved; but, upon leaving behind us theMesozoic era, all such detailed knowledge fails us. Erosion hasremoved vast thicknesses of the Paleozoic rocks, and all thatremain have been altered and crystallized by heat and mashedby irresistible forces while still buried deep within the earth.Such metamorphic rocks are the exposed foundations of ancient
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MS Lore Paleozoic lavas and huffs. i&i Paleozoic sediment. o. Scoie in miles .horizontal ondverricai. 10. 01111 P re -Pale ozoic complex gneisses. A-A Depth reached by later cycles of erosion. STRUCTURE SECTIONS of CENTRAL CONNECTICUT No. 23.) CENTRAL CONNECTICUT IN THE GEOLOGIC PAST. 33 mountains, but to what extent they were built at the end of thePaleozoic and to what extent in some of its earlier periods isunknown. The fact, however, that the mountains had becomeremoved by the middle of the Triassic period suggests that, al-though the crustal forces may have been intense during the lastmovements of the revolution which closed the Paleozoic, theelevation of the regions of subsequent Triassic sedimentation maynot have been great. The regions which were later occupied byTriassic rocks may already by the close of the Paleozoic haveformed intermontane depressions premonitory of the subsidenceof the Triassic. This conservative interpretation has beenadopted in the structure section.

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