. Bulletin of the Geological Society of America. Geology. 712 G. C. MARTIN TRIASSIC ROCKS OF ALASKA Pseudomonotis-bearing beds have a far wider distribution than the older Halobia-bearing beds, and that the intervening coral-reef limestone is even more restricted, occurring only near the present continental margin, also suggests an Upper Noric transgression following a Lower JSToric re- cession of the sea. The abrupt change in fauna! character from the sup- posedly warm-water Halobia zone to the boreal Pseudomonotis zone also. • U» Upper Triassic • M = Middle Triassic ioo o lOOMiles Figure 1.—
. Bulletin of the Geological Society of America. Geology. 712 G. C. MARTIN TRIASSIC ROCKS OF ALASKA Pseudomonotis-bearing beds have a far wider distribution than the older Halobia-bearing beds, and that the intervening coral-reef limestone is even more restricted, occurring only near the present continental margin, also suggests an Upper Noric transgression following a Lower JSToric re- cession of the sea. The abrupt change in fauna! character from the sup- posedly warm-water Halobia zone to the boreal Pseudomonotis zone also. • U» Upper Triassic • M = Middle Triassic ioo o lOOMiles Figure 1.—Map of British Columbia and Yukon, showing known Triassic localities suggests a withdrawal of the Karnic sea, followed by an Upper Noric transgression, presumably from the Arctic regions. The fauna of the McCarthy formation as now known includes Pseudo- monotis subcircularis (Gabb), Halobia sp., Pecten sp., and Arniotites (?) sp. The Pseudomonotis-bearing beds of the other Alaskan districts are correlated with the McCarthy formation on the basis of general lithologic similarity and sequence and also on the basis of the presence of Pseudo-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Geological Society of America. [New York : The Society]
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectgeology, bookyear1890
