Ammonite Fossil Research Articles

The K/T Trial

s with Programs 26:333. Johnson, K., and D. Nichols. 1994. Fossil plants and the Cretaceous Tertiary boundary in the northern great plains-the best terrestrial argument for an abrupt catastrophe. Geological Society of America, Abstracts with Programs 26:395. Keller, G. 1994. Global biotic effects of the KT boundary event: mass extinction restricted to low latitudes? Lunar and Planetary Institute Contribution 825:57-58. Markwick, P. J. 1994. Crocodilian distribution and diversity across the Cretaceous-Tertiary boundary. Implications for climatically induced extinction. Geological Society of America, Abstracts with Programs 26:395.s with Programs 26:395. Marshall, C. R. 1994. Using the ammonite fossil record to predict the position of the KT boundary Ir anomaly on Seymour This content downloaded from 207.46.13.57 on Fri, 09 Sep 2016 04:07:18 UTC All use subject to http://about.jstor.org/terms ^4M ATTT, CW T TWs RPCC)RD 247 Island, Antarctica. Geological Society of America, Abstracts with Programs 26:394. Raup, D. M., and D. Jablonski. 1994. Lack of selective extinction among end-Cretaceous bivalves. Geological Society of America, Abstracts with Programs 26:394. Schultz, P. 1994. Impact angle effects of global lethality. Geological Society of America, Abstracts with Programs 26:333. Sharpton, V. L., L. E. Marin, and B. C. Schuraytz. 1994. The Chicxulub multiring impact basin: evaluation of geophysical data, well logs, and drill core samples. Lunary and Planetary Institute Contribution 825:108-1 10. Sigurdsson, H., S. D'Hondt, and S. Carey. 1994. Impact extinction mechanisms: geochemistry of the target material. Geological Society of America, Abstracts with Programs 26:333. Zinsmeister, W. J., and R. M. Feldmann. 1994. Antarctica, the forgotten stepchild: a view of the KT extinction from the high southern latitudes. Lunar and Planetary Institute Contribution

A Different Opinion on the Geological Age of the Longzhaogou and Jixi Groups of Eastern Heilongjiang, China1

Abstract The age of the Longzhaogou and Jixi Groups of coal measures in eastern Heilongjiang were previously considered to be Jurassic or mainly Jurassic. But there occur Middle Barremian‐ Early Albian Aucellina ( bivalvia) fossils in the Upper Yunshan Formation of the Longzhaogou Group and the Lower Chengzihe Formation of the Jixi Group, and the Qihulin Formation of the Longzhaogou Group yields Early Cretaceous bivalve and ammonite fossils. Consequently, the geological ages of the two groups are mainly, or even all, Early Cretaceous.

Oatlands park grotto and its ammonite fossils

Oatlands park grotto and its ammonite fossils

Allochthonous Carbonate Debris in Mesozoic Flysch Deposits in Santa Ana Mountains, California

The Bedford Canyon Formation, in the Santa Ana Mountains, California, is predominantly a flysch-type sequence of alternating turbidite sandstones and pelagic shales. Within the dominant flysch sequence, however, are allochthonous limestone bodies, from 3 to 75 m long and 1.5 to 18 m thick. These limestones are commonly in abrupt contact with pebbly mudstones inferred to have been deposited primarily from submarine mass flows. The allochthonous limestones consist predominantly of clasts of shallow- and deep-water origin juxtaposed in a pervasive lime-mud matrix, which also includes both shallow-water crinoid and deep-water ammonite fossils. The carbonate debris was transported by submarine mass flows and was deposited essentially as thick units similar to the manner in which subaerial debris flows are deposited. Periods of deposition of the carbonate debris were short-term events during the long-term deposition of the surrounding detrital turbidite sands and pelagic shales. The Jurassic (Bajocian to Callovian) age of the allochthonous fauna contained in the Bedford Canyon limestones represents a maximum age limit for the allochthonous carbonate debris and, therefore, may not reflect the depositional age of the dominant sandstone-shale sequence. Consequently, the age of the Bedford Canyon Formation and its correlation with the Santa Monica Slate are uncertain. However, allogenic carbonate constituents in the detrital turbidites demonstrate that a shallow-water carbonate environment was present when the detrital sands and shales were forming. From stratigraphic relations, the youngest rocks of the Bedford Canyon Formation may be Albian (late Early Cretaceous) in age. In view of this interpretation and the strong lithologic similarities with Franciscan rocks, the Bedford Canyon Formation appears to represent a southern extension of the Franciscan Complex, which crops out predominantly north of the Transverse Ranges. The presence of a Mesozoic carbonate shelf, as demonstrated by the provenance of the Bedford Canyon limestones, represents a new paleogeographic province in southern California.

Geology in the academies of sciences

Geology in the academies of sciences

Definition and Age of Patagua Formation, Province of Aconcagua, Chile

The ammonite Olcostephanus and other fossils indicative of early Cretaceous age have been identified in the Patagua limestones, heretofore included as a member of the Jurassic Melon formation, in the Melon and La Ligua quadrangles. The new data lead to definition of the limestone series as a formation of Cretaceous age, and indicate that the Jurassic-Cretaceous boundary in central Chile should be redefined.

Upper Cretaceous in Western Peace River Plains, Alberta

The territory covered includes approximately 3,600 square miles of Plains area in north-central Alberta. The area is approximately 500 miles northwest of Edmonton, and its western edge parallels the Alberta-British Columbia boundary. The strata described comprise nearly 3,000 feet in the west, to 2,000 feet in the east, of Upper Cretaceous formations including, in ascending order, the Dunvegan, Kaskapau, Cardium (Bad Heart), Wapiabi, and basal Member A of the Wapiti. Within the area, the name Smoky River is raised from formational to group rank and includes the Kaskapau, Cardium, and Wapiabi formations. A White Speckled Shale zone was observed in the Kaskapau and another in the Wapiabi. It is suggested that the term Cardium as a formational name be extended eastward onto he plains and that it embrace the Bad Heart sandstone along Smoky River. The term Chinook is applied to a littoral marine sandy shale and sandstone member in the upper part of the Wapiabi shales. Both Ammonite and Inoceramus fossil zones are listed and correlated from west to east. Formational thicknesses are compiled from isolated outcrops. The formations thin notably eastward, particularly in the Smoky River group.

Roman Blast Furnace in Lincolnshire

Close to the hamlet of Woolsthorpe (the birth place of Sir Isaac Newton), in the parish of Colsterworth, Lincolnshire, on Thursday, 21st January 1932, the miners quarrying ore for the Frodingham Iron & Steel Co. unearthed a remarkably perfect furnace or bloomery of the Roman period. In shape it was box-like, roughly but carefully hand-moulded of grey indurated clay of the local Upper Lias formation; a fragment of an ammonite fossil was found in a crack. The length was nearly 3 ft., the upper or north-west end was about 22 in., and the lower or south-east end about 24 in. in width. The top was practically level and flat, but the bottom dipped, slightly from the northwest end for about 21 in., then very sharply, so that the depth increased from 15 in. at the north-west end to 21 in. at the other. The sides were irregular, about 6 in. thick at most, and in the middle of each was a tuyere hole, some 6 in. in diameter, sharply splayed externally. The ends were open; the north-west one was evidently the charging, and the other the tipping end. The actual bottom was only about half an inch thick of the same clay, but below this were 3 or 4 in. of a different bluish clay and under it some apparently partly burned oolitic limestone brought from near by. The natural soil is the ironstone whose quarrying led to the discovery of the furnace (pl. XLIV, fig. 1).