This paper uses detrital zircon (DZ) provenance and geochronological data to reconstruct paleodrainage areas and lengths for sediment-routing systems that fed the Cenomanian Tuscaloosa-Woodbine, Paleocene Wilcox, and Oligo cene Vicksburg-Frio clastic wedges of the northern Gulf of Mexico (GoM) margin. During the Cenomanian, an ancestral Tennessee-Alabama River system with a distinctive Appalachian DZ signature was the largest system contributing water and sediment to the GoM, with a series of smaller systems draining the Ouachita Mountains and discharging sediment to the western GoM. By early Paleocene Wilcox deposition, drainage of the southern half of North America had reorganized such that GoM contributing areas stretched from the Western Cordillera to the Appalachians, and sediment was delivered to a primary depocenter in the northwestern GoM, the Rockdale depocenter fed by a paleo-Brazos-Colorado River system, as well as to the paleo-Mississippi River in southern Louisiana. By the Oligocene, the western drainage divide for the GoM had migrated east to the Laramide Rockies, with much of the Rockies now draining through the paleo-Red River and paleo-Arkansas River systems to join the paleo-Mississippi River in the southern Mississippi embayment. The paleo-Tennessee River had diverted to the north toward its present-day junction with the Ohio River by this time, thus becoming a tributary to the paleo-Mississippi within the northern Mississippi embayment. Hence, the paleo-Mississippi was the largest Oligocene system of the northern GoM margin. Drainage basin organization has had a profound impact on sediment delivery to the northern GoM margin. We use paleodrainage reconstructions to predict scales of associated basin-floor fans and test our predictions against measurements made from an extensive GoM database. We predict large fan systems for the Cenomanian paleo-Tennessee-Alabama, and especially for the two major depocenters of the early Paleocene paleo-Brazos-Colorado and late Paleocene-earliest Eocene paleo-Mississippi systems, and for the Oligocene paleo-Mississippi. With the notable exception of the Oligocene, measured fans reside within the range of our predictions, indicating that this approach can be exported to other basins that are less data rich.

Antarctica's continental-scale ice sheets have evolved over the past 50 million years. However, the dearth of ice-proximal geological records limits our understanding of past East Antarctic Ice Sheet (EAIS) behaviour and thus our ability to evaluate its response to ongoing environmental change. The EAIS is marine-terminating and grounded below sea level within the Aurora subglacial basin, indicating that this catchment, which drains ice to the Sabrina Coast, may be sensitive to climate perturbations. Here we show, using marine geological and geophysical data from the continental shelf seaward of the Aurora subglacial basin, that marine-terminating glaciers existed at the Sabrina Coast by the early to middle Eocene epoch. This finding implies the existence of substantial ice volume in the Aurora subglacial basin before continental-scale ice sheets were established about 34 million years ago. Subsequently, ice advanced across and retreated from the Sabrina Coast continental shelf at least 11 times during the Oligocene and Miocene epochs. Tunnel valleys associated with half of these glaciations indicate that a surface-meltwater-rich sub-polar glacial system existed under climate conditions similar to those anticipated with continued anthropogenic warming. Cooling since the late Miocene resulted in an expanded polar EAIS and a limited glacial response to Pliocene warmth in the Aurora subglacial basin catchment. Geological records from the Sabrina Coast shelf indicate that, in addition to ocean temperature, atmospheric temperature and surface-derived meltwater influenced East Antarctic ice mass balance under warmer-than-present climate conditions. Our results imply a dynamic EAIS response with continued anthropogenic warming and suggest that the EAIS contribution to future global sea-level projections may be under-estimated.

Topography, sediment distribution, and heat flux are all key boundary conditions governing the dynamics of the East Antarctic Ice Sheet (EAIS). EAIS stability is most at risk in Wilkes Land across vast expanses of marine-based catchments including the 1400 km × 600 km expanse of the Wilkes Subglacial Basin (WSB) region. Data from a recent regional aerogeophysical survey (Investigating the Cryospheric Evolution of the Central Antarctic Plate (ICECAP)/IceBridge) are combined with two historical surveys (Wilkes basin/Transantarctic Mountains System Exploration-Ice-house Earth: Stability or DYNamism? (WISE-ISODYN) and Wilkes Land Transect (WLK)) to improve our understanding of the vast subglacial sedimentary basins impacting WSB ice flow and geomorphology across geologic time. Analyzing a combination of gravity, magnetic and ice-penetrating radar data, we present the first detailed subglacial sedimentary basin model for the WSB that defines distinct northern and southern subbasin isopachs with average sedimentary basin thicknesses of 1144 m ± 179 m and 1623 m ± 254 m, respectively. Notably, more substantial southern subbasin sedimentary deposition in the WSB interior supports a regional Wilkes Land hypothesis that basin-scale ice flow and associated glacial erosion is dictated by tectonic basement structure and the inherited geomorphology of preglacial fluvial networks. Orbital, temperate/polythermal glacial cycles emanating from adjacent alpine highlands during the early Miocene to late Oligocene likely preserved critical paleoclimatic data in subglacial sedimentary strata. Substantially thinner northern WSB subglacial sedimentary deposits are generally restricted to fault-controlled, channelized basins leading to prominent outlet glacier catchments suggesting a more dynamic EAIS during the Pliocene.

The problem of how to weight several predictors of a criterion in a linear model is discussed. It is argued that the recently recommended practice of replacing least squares weights (/3]$) with equal or simplified weights of standardized predictors will frequently result in serious, systematic errors of prediction. In particular, Wainer's equal weights theorem is shown to have little relevance to a wide range of prediction problems because, contrary to his claims, his assumptions are highly restrictive.A comprehensive algebraic system is described that makes explicit the interdependence between least squares regression coefficients and the set of correlations between all pairs of predictors as well as between each predictor and the criterion. Alternative sample-based estimators of population ftj values are discussed. It is argued that certain alternative f)j estimators can be expected to work particularly well when sample sizes are small and when predictor variables have substantial intercorrelations with one another. A general strategy is proposed for conducting applied prediction studies to take into account one's) prior beliefs or knowledge about covariances or correlations in the joint predictor-criterion system.A number of articles have recently appeared that have compared different weighting schemes for linear prediction models (Dawes & Corrigan, 1974;Einhorn & Hogarth, 1975;Schmidt, 1971). Interestingly, and perhaps surprisingly, all of these authors have found that simplified weighting of standardized predictors may be as good as or even superior to least squares weighting under rather general conditions. Wainer (1976) has recently offered a further analysis of this problem that is of particular interest, since his arguments were mathematical and his conclusions very general. He concluded that "when you are interested solely in prediction, it is a very rare situation that calls for regression weights which are unequal" (p. 216), In particular, Wainer provided a theorem that shows that under certain conditions, Requests for reprints should be sent to