Unit Name: Avalanche Formation
Unit Type: Lithostratigraphic
Rank: Formation
Status: Formal
Usage: Currently in use
Age Interval: Middle Cambrian (513 - 499 ma)
Age Justification: Trilobites.
Province/Territory: Northwest Territories; Yukon Territory
Originator: Gabrielse et al., 1973.
Type Locality:
Northeast limb of Broken Skull Anticline, 8 km (5 mi) southwest of Avalanche Lake (62°21'N, 127°20'W).
Distribution:
This formation is 396 m (1,300 ft) thick at the type section and occurs in the Glacier Lake, Flat River and Wrigley map-areas, District of Mackenzie and Yukon Territory.
Locality Data:
Thickness(m): Typical 396.
Lithology:
Buff, yellow and orange, maroon, pink and brown weathering, cryptograined to fine-grained dolomite, silty dolomite, dolomitic siltstone, and dolomitic mudstone. Pisolites are abundant in grey weathering dolomites. Mudcracks and salt casts are common.
Relationship:
It appears to be structurally conformable with the underlying Backbone Ranges Formation and is unconformably (angular) overlain by the Broken Skull Formation. The basal units of the Avalanche are correlative with the basal part of the Rockslide Formation.
References:
Gabrielse, H., Blusson, S.L., and Roddick, J.A., 1973. Geology of the Flat River, Glacier Lake and Wrigley Lake map-areas, District of Mackenzie and Yukon Territory; Geological Survey of Canada, Memoir 366 (Parts I and II), 421 p.
Source: CSPG Lexicon of Canadian Stratigraphy, Volume 2, Yukon Territory and District of Mackenzie; L.V. Hills, E.V. Sangster and L.B. Suneby (editor)
Contributor: L.V. Hills; H. Gabrielse
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 01 Dec 2010