Smithsonian miscellaneous collections (1916) (14802025863)

Identifier: smithsonianmisce641916smit (find matches)
Title: Smithsonian miscellaneous collections
Year: 1862 (1860s)
Authors: Smithsonian Institution
Subjects: Science
Publisher: Washington : Smithsonian Institution
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Smithsonian Libraries

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Text Appearing Before Image:
rom the thickly settled suburbin the southeastern portion of the city of Helena. In the diagram-matic section (fig. 10) the Helena limestone is represented as beingoverlain by formations that include Cambrian, Devonian, and Car-boniferous strata. No attempt is made to represent the character ofthe Cambrian in the sketch other than by a strong black line and linesabove it, since the point desired to be brought out in the section andthe text was the thinning out of the Helena limestone (Ah) and Em-pire shale (Ae) both from the east and west toward the SpokaneHills, and that a great unconformity was indicated by the fact thatthe Cambrian rested on the Spokane shales in the Spokane Hills withthe Helena limestone and Empire shale absent, and that in the BeltMountains as well as in the vicinity of Helena both of those forma-tions were present between the Spokane shales and the Cambrian. ^ Bull. Geol. Soc. America, Vol. 10, p. 211. ^The lettering used is the same as that on the map (pi. 39).
Text Appearing After Image:
,^a»°fe°-TherI?f;/f ^V^f °^. P.* f geological map of H alcott GuMfuV ^V P-i^ipa> fault lines! The>ilch fault, cuts through the formations on th.•--llie approximate line of the diagrammat elena aii<two most easterly, -Jhe eastern lowermatic section (fig. Si.^;;iiSy::i:l3^HHS¥^---^^^^ he westerly fault 26i a f sharel-(F)limitssec bri be^ vie Mi of Pa Be ha) anc bei am str we by in Le ma OV( boitheab(thepirHithetheM.tio NO. 4 CAMBRIAN AND PRE-CAMBRIAN AT HELENA 263 .2 u urn 1 sG e 264 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 64 Rothpletz states that he could not find the localities of Walcottsdiagrammatic figures 3 and 4 showing the unconformity betweenthe Cambrian and pre-Cambrian southeast of Helena. I find onlooking up my field notes of September 30, 1898, that I crossed fromthe west side to the east side of the city of Helena, and followed theoutcrop of the Flathead quartzite to the southeast and noted that ahalf mile east of the thickly settled southern section of

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