{{Short description|Geological formation in British Columbia}} {{Infobox Rockunit | name = Raspberry Formation | image = File:Raspberry Formation.png | caption = [[Paleogeological]] map of the Raspberry Formation at the end of the [[Volcanism of the Mount Edziza volcanic complex#Raspberry eruptive period|Raspberry eruptive period]] | type = [[Geological formation]]<ref name="Souther">{{Cite report|last1=Souther|first1=J. G.|author-link1=Jack Souther|title=The Late Cenozoic Mount Edziza Volcanic Complex, British Columbia|work=[[Geological Survey of Canada]]|publisher=Canada Communication Group|series=Memoir 420|year=1992|pages=3, 32, 47, 61, 249, 267|isbn=0-660-14407-7|doi=10.4095/133497|doi-access=free}}</ref> | age = {{Fossil range|11.4|5.5}} | period = Miocene | prilithology = [[Alkali basalt]], [[hawaiite]]<ref name="Souther"/> | otherlithology = | namedfor = [[Raspberry Pass]]<ref name="Souther"/> | namedby = [[Jack Souther|Souther]] ''et al.'', 1984<ref name="LCGU">{{cite web|url=https://weblex.canada.ca/html/012000/GSCC00053012505.html|title=Raspberry Formation|work=[[Lexicon of Canadian Geologic Units]]|publisher=[[Government of Canada]]|access-date=2023-08-04}}</ref> | year_ts = | region = [[British Columbia]]<ref name="Souther"/> | country = Canada<ref name="Souther"/> | coordinates = {{coord|57.5|N|130.6|W|display=inline,title}}<ref name="Edwards">{{cite thesis|last1=Edwards|first1=Benjamin Ralph|degree=PhD|title=Field, kinetic, and thermodynamic studies of magmatic assimilation in the Northern Cordilleran Volcanic Province, northwestern British Columbia|publisher=[[University of British Columbia]]|year=1997|page=10|isbn=0-612-25005-9}}</ref> | unitof = [[Mount Edziza volcanic complex]]<ref name="Edwards"/> | subunits = | underlies = [[Little Iskut Formation]]<ref name="Souther"/><br>[[Armadillo Formation]]<ref name="Souther"/> | overlies = [[Stikinia]]<ref name="Souther"/> | thickness = | extent = | area = | map = | map_caption = }} The '''Raspberry Formation''' is a [[stratigraphic unit]] of [[Miocene]] age in northwestern [[British Columbia]], Canada.
==Name== The Raspberry Formation takes its name from Raspberry Pass, a [[mountain pass]] cutting through the central portion of the [[Mount Edziza volcanic complex]].<ref name="Souther"/><ref>{{cite bcgnis|id=23319|name=Raspberry Pass|archive-url=https://web.archive.org/web/20211019052118/https://apps.gov.bc.ca/pub/bcgnws/names/23319.html|archive-date=2021-10-19|access-date=2023-04-17}}</ref>
==Geology== The Raspberry Formation has a volume of {{Convert|119|km3|mi3|abbr=on}}, making it the third most voluminous [[geological formation]] comprising the Mount Edziza volcanic complex.<ref name="Souther"/><ref name="Edwards"/> It varies in elevation from less than {{Convert|1310|m|ft|abbr=on}} along the [[Mess Creek Escarpment]] to {{Convert|1740|m|ft|abbr=on}} near [[Armadillo Peak]].<ref name="Souther"/>
The Raspberry Formation is overlain conformably by the [[Little Iskut Formation]]. An [[erosion surface]] separates the Raspberry Formation from the overlying [[Armadillo Formation]] and younger geological formations. Rocks of the [[Stikinia]] [[terrane]] underlie the Raspberry Formation.<ref name="Souther"/>
The Raspberry Formation consists of flat-lying [[alkali basalt]] and [[hawaiite]] flows. These flows are rusty brown and are [[interbedding|interbedded]] with reddish-brown to yellow or orange [[scoria]].<ref name="Souther"/> The Raspberry Formation represents three overlapping Miocene [[shield volcano]]es.<ref name="Edwards"/>
[[K–Ar dating]] 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.<ref name="Souther"/>
==See also== *[[Volcanism of the Mount Edziza volcanic complex]]
==References== {{reflist}}
{{Mount Edziza volcanic complex}}
[[Category:Geologic formations of the Mount Edziza volcanic complex]] [[Category:Miocene shield volcanoes]] [[Category:Shield volcanoes of Canada]] [[Category:Basalt formations]] [[Category:Miocene British Columbia]]