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Show DTK DESCRIPTIVE OF SOME GEOLOGICAL SECTIONS OF THE . COUNTRY ABOUT THE HEADWATERS OF THE MISSOURI AND YELLOWSTONE RIVERS. BY F. V. HAYDEN. It is not intended that these notes shall embrace a complete account | the geology of Montana. They are simply designed to render the ftutiful pictorial sections which accompany them more intelligible to fc general reader. That these pictorial sections may reach the public iner, an edition of them is issued in this form. All the sections in this < g^ Iper represent the scenery along the immediate valleys of the Lower l~~ Ttflatiu and Madison Rivers, with the exception of two, which are fine lustrations of different portions of the Yellowstone Valley. pt is hardly possible for the pencil of the artist to delineate more _ iftphically or minutely the scenery of this interesting country than > F8 6 sections do. For the geologist very little descriptive text is ^ 7 ieded, and for the details of the geology he is referred to the Annual '" ^ [ eports of the Survey for 1871 and 1872. • Should the Survey continue its operations from year to year by suit-ble grants of money from Congress, all the region, including the Yellow-lone National Park, will be re examined systematically and in detail; pat we have done up to this time must, therefore, be little more than preliminary to the more thorough work that must come hereafter. El have always regarded the junction of the three forks of the Mis- Inri- the Gallatin, Madison, and Jefferson- as one of the most interrupting geographical poihts along the Missouri River, Here, within a -- r^ lort distance of each other- a few hundred yards apart- these three Jreat streams unite in one, forming the Missouri River. This junction ' tinost admirably shown in Plate I, upper sketch, which is really a pan-amic view of the valley with the surrounding hills. The view is taken oking west from Gallatin Bluffs. At the right band, at a} the three rers have united into one channel, just at the upper end of a canon, or rge through Carboniferous limestones. In the bottom, and especially on the point between the Madison and Iferson Rivers, are remnants of Carboniferous limestone, with a few iracteristic fossils. These remnants are found at different points in 5 immediate valleys of these streams, showiug most clearly that the oad space now occupied with ihe lake- deposits, between the Jefferson -^ id Gallatin Rivers, was originally worn out of the sedimentary beds of I s locality. In other words, we obtain in this way a glimpse of the knendous magnitude of the erosive action in past times in this re-pn. In the background are weathered hills, rising from 600 to 1,200 feet bve the valley, underlaid, for the most part, with the limestones of frboniferous age^ inclining toward the north or northeast. Other for- • tions come in, farther and farther in the background, as the Juras- No. 3 1 |
