Open File: Nfld/2401, compiled by M.J. Batterson and published March 1994; revised in 2001.
This compilation provides a list of all currently available surficial and aggregate geology maps for Newfoundland and Labrador. The maps are listed by NTS map sheet, and are mostly at scales of 1:50,000 or 1:250,000. Maps are available as blue line, printed black line or colour maps, and digital on demand colour maps. For ease of searching, information is listed by 1:250,000 scale NTS map sheet, and is divided into 4 separate categories.
Maps are listed under the headings of Ice Flow, Surficial Geology and Aggregate Geology. A section of pertinent Current Research articles is also included because these reports commonly compliment the associated mapping.
Description of Map Types
For information on surficial and aggregate publications, see Surficial Geology & Aggregate Maps for Newfoundland and the Geofiles Database. In the database search Document Type = All GSNL Maps and Keyword = Surficial Geology/Geomorphology and title equals either ‘ice’, ‘surficial’ or ‘aggregates’ to get a list of references.
Ice Flow Maps
These maps provide data used to reconstruct the directions and sequences of glacial advances during the Quaternary. Most of the data are from striations, and are presented as directional or non-directional indicators. A direction is assigned to a striation where features such as nailheads, miniature rat tails, or outcrop stossing were identified on a rock surface which unequivocally define the direction of glacial movement. Where these features were not found a non-directional orientation is applied. Where more than one set of striations are found at a site, the relative age can be determined from either cross-cutting relationships or the preservation of one set of striae in the lee of a later set. Where a clear age relationship can be determined a relative age is assigned, with 1 being the oldest. Where no clear relationship is seen, no relative age is assigned. Some maps present ice flow data derived from clast fabrics measured from tills. Clast fabrics describe the orientation and dip of elongate clasts within a sediment. Elongate clasts will align themselves parallel to flow lines in a glacier and this orientation may be preserved if the clasts are deposited beneath the ice. Thus, the orientation of clasts in sediment (clast fabric) can be used to determine the direction of ice flow that deposited the sediment. The fabric data shows the last ice flow to have affected the sediment
Most maps under the ice flow heading present only ice flow data. Some maps however, are surficial geology maps on which ice flow data is recorded.
Surficial Geology Maps
Surficial geology maps provide data on the types of material and landforms found at the surface. These maps are largely derived from aerial photograph interpretation with a variable amount of field checking. On some maps a reliability diagram is attached which outlines the amount of field checking. Each map has a detailed legend attached that describes the characteristic of each sediment type and feature encountered. The legend has a genetic category that defines the sediment type (e.g., glacial, fluvial, aeolian), and a morphology category that describes the surface expression (e.g., veneer, blanket, hummocky, fan). Most mapped units contain more than one genetic and/or morphological type. To accommodate this, units are subdivided by decreasing dominance (e.g., Tv/Rc means that the area is dominantly a veneer of glacial sediment, with a lesser area of bedrock concealed by a mat of vegetation). Up to three genetic or morphological categories can be accommodated on the maps, with a combination of slashes (/ or //) and hyphens (-) being used to indicated relative proportions. The maps provide only a general indication of sediment characteristics and some variability in sediment is to be expected across a map area. A till, for instance, may have a silty texture in one part of the area, and be sandier elsewhere, although both areas will have the T designation. Similarly, overburden thickness can only be inferred from these maps.
Aggregate Geology Maps
These maps provide data on granular or bedrock aggregates within an area. Granular aggregate maps outline sand and gravel deposits, and categorise each deposit by their potential as an aggregate producing area, with Zone 1 having the highest potential. Recent maps commonly include grain size and petrographic data. Sample data, including grain size and petrographic analyses, related to other map areas can be obtained from the Terrain Sciences Section, Geological Survey Branch, Telephone1-709 729-3888. Potential reserves of material are approximated based on the aerial extent and depth of natural or man-made exposures. Detailed descriptions are commonly provided in associated Current Research articles.