Also known as North of Big Hole River; South side of McCarty's Mountain; McCartney Mountain; MV 5813; MV 5908; MV 6201; MV 6202
Where: Madison County, Montana (45.5° N, 112.6° W: paleocoordinates 47.3° N, 103.8° W)
• coordinate stated in text
When: Chadron Formation (White River Group), Chadronian (37.2 - 33.9 Ma)
• "Titanotherium beds, Lower White River formation" - Gilmore 1928.
•Lower White River/Titanotherium beds = Chadron Fm (Hoganson et al., 1998)
Environment/lithology: wet floodplain; fine-grained, quartzose, gray tuff
•The water table must have been very near and in places above the surface providing conditions too moist for large trees, but suitable for shrubs and other low vegetation. Frequent and widespread flooding of the floodplain by sluggish streams took place. The flooding could be the result of rainfall or could be caused by faulting and/or plugging of the watercourses by lava and ash from the widespread volcanic activity in the area as postulated by Pardee (1950), Freeman, Ruppel, and Klepper (1958), and Mann (1954). The lower and upper beds in the measured section were deposited at the basin margin as indicated by the very large boulders of andesite brought into the sediment by swift-flowing small tributary streams. The lack of channels in the middle beds could indicate that the margin of the basin had shifted and the area of deposition was no longer at the edge of the basin. Renewed faulting might explain the re-occurrence of tributary channels in the upper beds. However, the lock of any unconformity within the sequence argues against this interpretation.
Size classes: macrofossils, mesofossils
Collected by Earl Douglass
Primary reference: E. Douglass. 1905. The Tertiary of Montana. Memoirs of the Carnegie Museum 2(5):203-221 [J. Alroy/J. Alroy/J. Marcot]more details
Purpose of describing collection: general faunal/floral analysis
PaleoDB collection 16990: authorized by John Alroy, entered by John Alroy on 15.05.2002, edited by Jonathan Marcot, Terri Cleary and Evangelos Vlachos
Creative Commons license: CC BY (attribution)