The dataset includes subsurface stratigraphic picks for the top of the Foremost Formation (Belly River Group) in the Alberta Plains (Townships 1 to 52, Ranges 1W4 to 5W5) made from downhole wireline geophysical well logs. The top of the Foremost was picked at the base of a continuous sandstone or siltstone bed (low-gamma-ray) of variable thickness overlying the Taber coal zone. Well data were screened to detect errors resulting from deviated wells, as well as incorrect ground and kelly bushing elevation data. We used statistical methods to identify local and regional statistical outliers, which were examined individually.

A digital grid of the top of the Empress Formation where present, or the topography of the surrounding landscape, where the formation is absent. This includes the units 1 to 3 of the Empress Formation in buried valleys, as well as undifferentiated Empress interfluve sediments resting on the bedrock surface between buried valleys. The unit is originally modelled from borehole data and adjusted to the bedrock surface, the surfaces of units 1, 2, 3 and interfluve units of the Empress Formation, and the present-day land surface. The grid is generated at a 250 metre cell-size resolution, based on 2003 information.

The surficial material dataset was developed as part of the Western Economic Partnership Agreement (WEPA) project covering all of NTS 73M, the southern three-quarters of 74D and southeast part of 84A. Part of the dataset was compiled by airphoto interpretations and followed by random ground-truthing by AGS geologists (NTS 73M). The dataset was later merged with other existing surficial geology maps (74D and 84A). The mapping scheme chosen for the 1:50 000 scale terrain classification is a variant of the scheme used in Alberta Geological Survey Bulletin 57 to map the surficial geology of the Sand River area (Map 178), NTS 73L, directly south of the study area. In this terrain classification scheme, each map unit includes a component of genesis, morphology and relief. Where available, additional information regarding the properties of the genetic unit was included as a genetic modifier. For example, the map unit 'sMh1' denotes hummocky (h), low relief (1), sandy (s) moraine (M). Genesis of geological material is considered to be the primary component of the map unit thus colours on the map depict differences in genesis. In the above example, the map unit colour would correspond to the legend colour chosen for moraine (M). An attempt has been made to reclassify the surficial geological units depicted in the surficial geology map of area NTS 74D (Map 148) using this mapping scheme, without significantly changing the polygon shapes of that previous work.

This is a 1000 m cell-sized raster dataset of the upper surface of the Sunchild Aquifer, modelled from the >55% sand point data derived by depth-slice analysis of well-log data. Alberta Geological Survey Bulletin 66 provides details on this grid dataset. The dataset is in ESRI ASCII grid format.

The dataset includes subsurface stratigraphic picks of the tops of the Horseshoe Canyon/Wapiti and Battle formations in the west-central Alberta Plains (Townships 15 to 67, Ranges 16W4 to 3W6) made from wireline geophysical well logs. The dataset supplements Alberta Geological Survey Open File Report 2011-08, which describes the methodology. We screened the well data to detect errors resulting from deviated wells, as well as incorrect well-header ground and kelly bushing elevation data. Statistical methods identified local and regional statistical outliers, which were examined individually.

The dataset includes subsurface stratigraphic picks for the top of the Oldman Formation (base of the Dinosaur Park Formation) in the Alberta Plains (Townships 1 to 47, Ranges 1W4 to 5W5) made from wireline geophysical well logs. The dataset supplements Alberta Geological Survey Open File Report 2011-13, which describes the methodology used to make the picks. Well data were screened to detect errors resulting from deviated wells, as well as incorrect ground and kelly bushing elevation data. We used statistical methods to identify local and regional statistical outliers, which we examined individually.

A digital grid of the top of the Empress Fm. Unit 3 sand and gravel, (the uppermost unit in the Empress Formation), where present, or the topography of the surrounding landscape, where Unit 3 is absent. The unit is originally modeled from borehole data and adjusted to the bedrock surface, the surfaces of units 1 and 2 of the Empress Formation, the and present-day land surface. The grid is generated at a 250 m cell-size resolution, based on information as recent as 2003.

Preliminary Interpretive Report 2021-3, Measured stratigraphic section in the upper Schrader Bluff Formation (Late Campanian-Maastrichtian?), Ivishak River, Alaska, presents results of U-Pb zircon geochronology analysis of an airfall-tephra deposit sampled from approximately 755.5 m above the base of the measured section. Zircon grains were separated and analyzed by Apatite to Zircon, Inc. via laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). The U-Pb age is the first published robust radioisotopic age constraint for Upper Cretaceous rocks on the east-central North Slope. Thirty zircons were analyzed, yielding a range of dates (and uncertainties) that exceed the amount of dispersion expected for a single eruptive event. In order to derive a statistically valid and geologically reasonable eruption age, a weighted mean was calculated using a subset of the youngest grains. Grain date selection criteria for this subset is modeled after the detrital zircon literature where a variety of techniques have been proposed to derive maximum depositional ages (MDAs) for strata based on the youngest grain or grains within a sample. In this case, we favored a method for MDA calculation that selects a subpopulation based on the youngest cluster of three or more dates that overlap at +/- 2 sigma analytical uncertainty. A subpopulation of 20 out of 30 grains satisfied this selection criteria and resulted in a weighted mean age of 71.13 +/- 1.24 Ma. The reported weighted mean age 2 sigma uncertainty reflects both analytical uncertainty and an additional (generic) 1.5 percent (2 sigma) systematic uncertainty component. The new U-Pb age indicates the upper part of the measured section was deposited in the Early Maastrichtian. All files are available from the Alaska Division of Geological & Geophysical Surveys (DGGS) website: http://doi.org/10.14509/30693.