Surficial Geology

Surficial Geology


Legend

RECENT DEPOSITS

10- ORGANIC DEPOSITS: mainly muck and peat in bogs and poorly drained areas
9- MODERN RIVER DEPOSITS: stratified sand, silty sand, silt, and disseminated organic matter on flood plaine of present rivers
L- Landslide areas; includes zones of both material removal and redeposition

POST-CHAMPLAIN SEA DEPOSITS

8- ABANDONED RIVER CHANNEL DEPOSITS: silt and silty clay; commonly including lenses of sand and generally underlain at variable depth by unit 3
7- ABANDONED RIVER CHANNEL DEPOSITS: stratified, buff, medium grained sand; unfossiliferous; locally reworked into low dunes
6- ESTUARINE AND CHANNEL DEPOSITS: stratified, buff to gray, medium to fine grained sand; minor gravel lenses; unfossiliferous; locally reworked into low dunes

CHAMPLAIN SEA DEPOSITS

5- LITTORAL FACIES: gravel, coarse sand and cobbles; containing fossils; in places composed of slabs of bedrock where beach was derived from outcrops of Paleozoic rock. (Beaches underlain by fluvioglacial deposits are mapped as unit 2)
4- SUB-LITTORAL FACIES: uniform, fine, buff sand deposited in shallow water as nearshore facies; commonly reworked into dunes; commonly fossileferous
3- DEEP WATER FACIES: blue-gray clay, silt, and silty clay; calcareous and fossiliferous at depth; commonly reworked; non-calcareous and non-fossiliferous at surface (0-2 m) particulary in northeastern part of area

PRE-CHAMPLAIN SEA DEPOSITS

2- FLUVIOGLACIAL DEPOSITS: gravel and sand, stratified, some till; in form of eskers and various ice-contact deposits; surface reworked into beaches in locations below the Champlain Sea marine limit
1- GLACIAL DEPOSITS: till; heterogeneous mixture of material ranging from clay to large boulders, generally sandy, grades downwards into unmodified till; surface generally modified by wave or river action; topography flat to hummocky

BEDROCK

R2- Limestone, dolomite, locally shale, sandstone (Paleozoic); mainly bare, tabular outcrops; includes areas thinly veneered by unconsolidated sediments up to 2 m thick
R1- Intrusive and metamorphic rocks (Precambrian); mainly bare, hummocky, rolling or hilly rock knob upland; includes areas thinly veneered by unconsolidated sediments up to 2 m thick
Bˇlanger, J. R., Howard, M., Moore, A. and Prˇgent, A.
Surficial Geology Maps of Canada Reference Database. GSC Open File 2885
Digital map of Surficial Materials and Terrain Features of the National Capital area. Previously released on paper at the scale of 1:125000 (GSC Map 1425A) the map has been digitized and processed by GIS and is released in E00 format.

Source: Map 1425A (Geological Survey of Canada) http://sts.gsc.nrcan.gc.ca/page1/urban/map1.htm