Abstract Recent work by a multi-disciplinary team has led to a significantly better understanding of the prospectivity of the North Red Sea. New regional biostratigraphic and environmental analysis from north to south through the Gulf of Suez and into the Red Sea have placed the Nubian sequences into a regional chronostratigraphic framework. The Nubian Upper Cretaceous pre-rift sandstones are observed in the field on both the Egyptian and Saudi Arabian side of the North Red Sea. This regionally extensive sequence was deposited in a continental to shallow marine setting fringing the Mesozoic Tethys Ocean, which lay further north. Extensive onshore fieldwork and mapping of sediment input points, fault orientations and fault linkages have helped to develop an understanding of the expected controls on syn-rift sandstone and carbonate deposition offshore. Thick halite with interbedded evaporite and clastics in the Late Miocene sequences of the Red Sea pose seismic imaging challenges. Recent reprocessing and newly acquired seismic data have produced a step change improvement in imaging of the prospective pre-rift section. Petroleum systems modelling incorporating new information on rift timing and crustal thinning as well as onshore core analysis for source rock properties and temperature variation through time indicates that oil expulsion occurs in the inboard section of North Red Sea – Block 1. This is supported by hydrocarbon shows in the drilled offshore wells which can be typed to pre-rift source rocks from stable isotope and biomarker data. All the key elements of the Gulf of Suez petroleum system exist in the North Red Sea. An integrated exploration approach has enabled prospective areas in the North Red Sea – Block 1 to be high-graded for drilling in early 2011.

The International Continental Scientific Drilling Program (ICDP)–U.S. Geological Survey (USGS) Eyreville A and B drill cores sampled crater fill in the region of the crater moat, ~9 km to the NE of the center of the Chesapeake Bay impact structure, Virginia, USA. They provide a 953 m section (444–1397 m depth) of sedimentary clast breccia and intercalated sedimentary and crystalline megablocks known as Exmore beds, deposited on top of the impactite sequence between 1397 and 1551 m depth. We petrographically investigated the sandy-clayey groundmass-dominated breccia, which resembles a diamictite (“Exmore breccia”), and which, in its lower parts, carries sedimentary and crystalline blocks. The entire breccia interval is characterized by the presence of glauconite and bioclastic carbonate, which distinguishes the Exmore breccia from other sandy facies above and below in the stratigraphy. The sediment-clast breccia exhibits strong heterogeneity from sample to sample with respect to groundmass nature, e.g., clay versus sand content, as well as clast content, in general, and shocked clast content, in particular. There is a consistently significantly larger macroscopic sedimentary to crystalline clast content. On the microscopic scale, the intersample sediment to crystalline clast ratios are quite variable. A very small component of shocked material, in the form of shock-deformed quartz, and to an even lesser degree feldspar, and somewhat more abundant but still relatively scarce shard-shaped, altered melt particles, is present throughout the section. However, between ~458 and 469 m, and between 514 and 527 m depths, the abundance of such melt particles is notably enhanced. These sections are also chemically distinct and relatively more mafic than the other parts of the Exmore breccia. It appears that from the time of deposition of the 527 m material, calming of the ocean occurred over the crater area as a result of abatement of resurge activity, so that ejecta from the plume above the crater could accumulate within the crater area to a larger degree. Deposition of ejecta fallout from the collapsing ejecta plume was terminated by the time of deposition of the 458 m material. This raises questions about the positioning of the exact upper contact of Exmore breccia to post-Exmore sediment (Chickahominy Formation), which is currently placed at 444 m depth and which possibly should be revised to 458 m depth. Based on a significant record of granite-derived material with shocked minerals, the shocked debris component seems to be largely derived from crystalline target rocks. This provides further evidence that the basement-derived material of the basal section of the Eyreville drill cores, which is essentially unshocked, is likely of an allochthonous nature and that the drilling did not intersect the actual crater floor.

Abstract The lower sandstone unit of the Upper Cretaceus Eagle Sandstone is extensively exposed in a 300-ft (100-m) high cliff which is dangerously sheer in places and rises above the north edge of Billings, Montana (Fig. 1). An excellent view of the cliffs from a distance can be seen from Rocky Mountain College. The safest and most accessible place to examine the outcrop is in Swords Park, a city park open to the public and accessible by two-wheel drive vehicles.

Abstract As geologist and director of the Texas Bureau of Economic Geology, J. A. Udden gained a reputation as a pioneer geologist from 1911–1932. Less is known about Udden’s tenure at Augustana College in Rock Island, Illinois, from 1888–1911. A study of letters to and from his teacher, students, and sons during this period, in light of some of his key tum-of-the-century publications, shows the influence of Udden’s research at Augustana. Many of the concepts which brought him recognition later in life were developed under the guidance of his Augustana teacher, Josua Lindahl. As early as 1891, Udden advocated an actualistic approach to geology much like that of Johannes Walther. Udden’s research on wind-blown sediments led to the development of a particle distribution scheme that is used by sedimentologists today—the Udden-Wentworth scale. Working with T. C. Chamberlin, Udden was one of the first geologists to demonstrate that the Pleistocene loess of the Upper Mississsippi Valley was a wind-blown, not water-laid sediment. His interest in wind led to the construction of a working model of a flying machine. He perceived the importance of drill cuttings long before the oil and gas industry realized their value in subsurface geology. An interest in electricity led to Udden’s recommendation of seismic reflection as an exploration tool for oil and gas. Despite a full-time teaching load, Udden published 46 papers during his 23 years at Augustana.