Scales of Heterogeneity of a Leveed-channel System, Cretaceous Dad Sandstone Member, Lewis Shale, Wyoming, USA
Roger M Slatt, Jonathan Minken, Staffan K Van Dyke, David R Pyles, Alan J Witten, Roger A Young, 2008. "Scales of Heterogeneity of a Leveed-channel System, Cretaceous Dad Sandstone Member, Lewis Shale, Wyoming, USA", Atlas of Deep-Water Outcrops, Tor H. Nilsen, Roger D. Shew, Gary S. Steffens, Joseph R. J. Studlick
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The Cretaceous Lewis Shale-Fox Hills-Lance Formations in southern Wyoming (Figure 1) were deposited during the final transgressive-regressive cycle of the Cretaceous western interior seaway (Figure 2). These formations comprise a third-order highstand systems tract (Figure 3) composed of several fourth-order lowstand-highstand cycles. One of these fourth-order cycles is well exposed in three outcrops — called Spine 1, Spine 2, and Rattlesnake Ridge — over a distance of 3.2 km (2 mi) (Figure 4). The strata within these outcrops are important for two reasons: 1) they provide good outcrop exposures of the Lewis Shale in an area of active exploration for gas, and 2) the Dad Sandstone Member of the Lewis Shale here is considered to be an excellent, scaled analog of delta-fed, mud-dominated, progradational, turbidite systems that are hydrocarbon-productive in areas such as the Gulf of Mexico and offshore west Africa.
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Tor H. Nilsen, a red-haired Scandinavian who stood more than six feet tall, died October 9, 2005, at his San Carlos, California, home. This was after a valiant five-year fight with melanoma cancer. He was 63. His ashes were scattered at his family plot in Norway in 2006.
He was born in New York City on November 29, 1941, to Mollie Abrahamson and Nils Marius Nilsen of Mandal, Norway, and was the first of their children to be born in the United States. After graduating from Brooklyn Tech, he earned his B.S. in geology from City College of New York in 1962. While there, his prowess on the basketball court impressed a scout from the New York Knicks, but Tor went on to graduate school and earned his M.S. and Ph.D. degrees in geology from the University of Wisconsin at Madison in 1964 and 1967, respectively. His M.S. thesis was a study of Precambrian metasedimentary deposits in the Lake Superior area, and his Ph.D. thesis was a study of Devonian alluvial-fan deposits of the Old Red Sandstone in western Norway.
Dr. Nilsen’s principal expertise was in depositional systems analysis, stratigraphic analysis, and the relationships among tectonics, eustasy, and sedimentation. He began his industry career in 1967 as a research geologist with the Shell Development Company in Houston, Texas, and Ventura, California, where he worked on the tectonics and sedimentation of Tertiary shelf systems of coastal California. He subsequently spent two years with the U.S. Army Corps of Engineers as the Military