BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



VOL. 17, PP. 541-566, PLS. 73~79 DECEMBER 31, 1906 



FISH KEMAINS IN OKDOVICIAN EOCKS IN BIGHORN 



MOUNTAINS, WYOMING, WITH A KfiSUMfi OF 



ORDOVICIAN GEOLOGY OF THE 



NOETHWEST 



BY N. H. DARTON* 



{Presented in abstract before the Society December 29, 1905) 



CONTENTS 



Page 



Introduction , 542 



General geology of the Bighorn uplift , 542 



Geography 542 



Structure 542 



Rocks 543 



Ordovician of the Bighorn mountains. 544 



General relations 544 



Character 545 



Thic: ess 546 



Stratigraphic relations . . . 547 



Invertebrate fossils 548 



Occurrence of the fish remains 550 



Age of Bighorn formation 552 



Ordovician in Owl Creek mountains 552 



Ordovician in northwest Wyoming and Montana 553 



Ordovician in western Wyoming 554 



Ordovician in the Black Hills uplift 555 



Absence of Ordovician in Laramie mountains 556 



Absence of Ordovician in Hartville uplift 556 



Ordovician in eastern Colorado 556 



General extent and relations 556 



Manitou limestone 557 



Harding sandstone 557 



Fremont limestone 557 



Relations in Garden Park region 559 



Relations west of Canyon City 560 



Fish remains and associated fossils near Canyon City 563 



Harding quarry locality 563 



Manitou region 564 



Deadman creek 565 



Perry park 565 



Resume 565 



* Published by permission of the Director of the U. S. Geological Survey. 



]>-Bull. Geol. Soc. Am., Vol. 17, 1905 (541) 



