The Raspberry Formation is a
stratigraphic unit of
Miocene age in northwestern
British Columbia, Canada.
Naming
The Raspberry Formation takes its name from Raspberry Pass, a
mountain pass
A mountain pass is a navigable route through a mountain range or over a ridge. Since many of the world's mountain ranges have presented formidable barriers to travel, passes have played a key role in trade, war, and both Human migration, human a ...
cutting through the central portion of the
Mount Edziza volcanic complex.
Geology
The Raspberry Formation has a volume of , making it the third most voluminous
geological formation comprising the Mount Edziza volcanic complex.
It varies in elevation from less than along the
Mess Creek Escarpment The Mess Creek Escarpment is an escarpment in northwestern British Columbia, Canada, located on the east side of Mess Creek below Mess Lake and southeast of Telegraph Creek. It forms the central-western flank of the Mount Edziza volcanic complex, ex ...
to near
Armadillo Peak.
The Raspberry Formation is overlain conformably by the
Little Iskut Formation
The Little Iskut Formation is a stratigraphic unit of Miocene age in northwestern British Columbia, Canada.
Naming
The Little Iskut Formation takes its name from the Little Iskut River, a tributary of the Iskut River which flows southeast from ...
. An
erosion surface separates the Raspberry Formation from the overlying
Armadillo Formation and younger geological formations. Rocks of the
Stikinia
Stikinia, or the Stikine terrane, is a terrane in British Columbia, Canada; the largest of the Canadian Cordillera. It formed as an independent, intraoceanic volcanic arc during the Paleozoic and Mesozoic.
Stikinia forms the bedrock of numerous v ...
terrane underlie the Raspberry Formation.
The Raspberry Formation consists of flat-lying
alkali basalt and
hawaiite flows. These flows are rusty brown and are
interbedded
In geology, interbedding occurs when beds (layers of rock) of a particular lithology lie between or alternate with beds of a different lithology. For example, sedimentary rocks may be interbedded if there were sea level variations in their sedimen ...
with reddish-brown to yellow or orange
scoria.
The Raspberry Formation represents three overlapping Miocene
shield volcano
A shield volcano is a type of volcano named for its low profile, resembling a warrior's shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more v ...
es.
has yielded ages of 11.4 ± 1.5 million years, 8.4 ± 0.4 million years and 6.4 ± 0.3 million years for Raspberry hawaiite and 6.1 ± 0.4 million years and 5.5 ± 0.1 million years for Raspberry alkali basalt.
See also
*
Volcanism of the Mount Edziza volcanic complex
References
{{reflist
Geologic formations of the Mount Edziza volcanic complex
Miocene Canada
Miocene shield volcanoes
Shield volcanoes of Canada
Basalt formations