| Mount Fee | |
|---|---|
 Mount Fee as seen from Metal Dome | |
| Highest point | |
| Elevation | 2,162 m (7,093 ft)[1] |
| Prominence | 312 m (1,024 ft) |
| Coordinates | 50°04′59″N123°15′00″W / 50.08306°N 123.25000°W /50.08306; -123.25000[1] |
| Geography | |
  Mount Fee Location in British Columbia | |
 | |
| Interactive map of Mount Fee | |
| Location | Location in British Columbia |
| District | New Westminster Land District |
| Parent range | Pacific Ranges |
| Topo map | NTS 92J3Brandywine Falls |
| Geology | |
| Rock age | Unknown[1] |
| Mountain type(s) | Eroded volcano,[1]stratovolcano |
| Volcanic arc | Canadian Cascade Arc[2] |
| Volcanic belt | Garibaldi Volcanic Belt[2] |
| Volcanic field | Mount Cayley volcanic field[2] |
| Last eruption | Unknown;Pleistocene age[1] |
Mount Fee is a volcanic peak in thePacific Ranges of theCoast Mountains in southwesternBritish Columbia,Canada. It is located13 km (8.1 mi) south ofCallaghan Lake and21 km (13 mi) west of theresort town ofWhistler. With a summit elevation of2,162 m (7,093 ft) and atopographic prominence of312 m (1,024 ft), it rises above the surrounding rugged landscape on an alpine mountain ridge. This mountain ridge represents the base of a north-south trendingvolcanic field which Mount Fee occupies.
The mountain consists of a narrow north-south trending ridge of fine-grainedvolcanic rock and small amounts of fragmental material. It is1.5 km (0.93 mi) long and0.5 km (0.31 mi) wide with nearly vertical flanks. Mount Fee has two main summits, the southern tower of which is the highest. The summits are separated by a U-shaped crevice that gives them a prominent appearance.
Mount Fee is one of the southernmost volcanoes in theMount Cayley volcanic field. This volcanic zone forms the central portion of the largerGaribaldi Volcanic Belt, which extends from theSilverthrone Caldera in the north to theWatts Point volcano in the south.[3] Thevolcanic belt has formed as a result of ongoingsubduction of theJuan de Fuca Plate under theNorth American Plate at theCascadia subduction zone along theBritish Columbia Coast.[4] This is a north-south trending fault zone about1,000 km (620 mi) long, extending80 km (50 mi) off thePacific Northwest fromNorthern California to southwestern British Columbia. The plates move at a relative rate of over10 mm (0.39 in) per year at an oblique angle to the subduction zone.[5]
The edifice of Mount Fee is the remains of a volcanic feature that has been significantly eroded by glacial ice.[1] It likely represents a dissectedstratovolcano (also known as a composite volcano) that was larger in area and higher in elevation than its current form.[6] Stratovolcanoes can reach heights of2,500 m (8,000 ft) and consist of alternating layers of lava flows,volcanic ash,cinders,blocks andbombs.[7] During the glacial periods, much of the volcano's original outer cone of pyroclastic material was eroded away by moving layers of ice and rock. The removal of the ejected volcanic material has exposed thedacite lava that forms the narrow north-south trending ridge of Mount Fee.[6]The Black Tusk, a pinnacle of dark volcanic rock to the southeast, is also interpreted to be the remains of a deeply eroded volcano that was once covered with pyroclastic material.[8] The present day edifice of Mount Fee contains severallava spines that reach heights of100 m (330 ft) to150 m (490 ft) above the main ridge.[2]
Volcanic activity at Mount Fee is among the oldest in the Mount Cayley volcanic field. Its volcanic rocks remain undated, but the large amount of dissection and evidence of glacial ice overriding the volcano indicates that it formed more than 75,000 years ago before theWisconsinan Glaciation. As a result, the rocks comprising Mount Fee do not display evidence of interaction with glacial ice; the duration of volcanic events is unknown, and the exact timing of eruptive events is unknown.[1] However, a large variety of volcanoes formed subglacially between 25,000 and 10,000 years ago in the vicinity of Mount Fee, including thelava domes ofEmber Ridge to the south.[9]
At least three phases of eruptive activity have been recognized at Mount Fee. The only exposed remnant of Fee's earliest volcanic activity is a minor outcrop of pyroclastic rock. This is evidence ofexplosive eruptions during Fee's eruptive history, as well as its first volcanic event. The second volcanic event produced a sequence of volcanic rocks on Fee's eastern flank. This volcanic material was likely deposited when a sequence of lava flows and broken lava fragments erupted from a volcanic vent and moved down the flanks during the construction of the ancestral Mount Fee. Following extensive dissection, renewed volcanism produced a viscous series of lavas on its northern flank. The U-shaped crevice separating the two main summits of Mount Fee separates this lava flow from the main volcanic ridge. The conduit from which these lava flows originated was likely vertical in structure and intruded through older rocks deposited during Fee's earlier volcanic events. This volcanic event was also followed by a period of erosion, and likely one or moreglacial periods. Extensive erosion following the last volcanic event at Mount Fee has created the rugged north-south trending ridge that currently forms a prominent landmark.[1]
The dacite and rhyodacite rocks comprising Mount Fee contain up to 70% brownvolcanic glass and up to 15%vesicles. About 25% of the rocks contain crystal content, includingplagioclase,hornblende,orthopyroxene,orthoclase and sporadicquartz. The orthoclase crystals are interpreted to represent rock fragments that became enveloped during hardening of the dacitic lavas. A portion of the southwestern flank of Mount Fee comprises no volcanic glass, but rather composed of an abnormalcryptocrystallinematrix. This indicates that it might have developed as part of asubvolcanicintrusion.[2]
Human habitation at Mount Fee extends from hundreds to thousands of years ago. Glassy volcanic rocks, such as rhyodacite, were widely used to make knives, chisels, adzes and other sharp tools before the arrival ofEuropeans in the 18th century. It was collected from a number of minor outcrops on the flanks of Mount Fee, as well as atMount Cayley andMount Callaghan. This material appears in goat hunting sites and at the Elaho rockshelter, collectively dated from about 100 to 8,000 years ago.[10]
In September 1928, Mount Fee was named by British mountaineer Tom Fyles after Charles Fee (1865–1927), who was a member of theBritish Columbia Mountaineering Club inVancouver at the time.[11] Subsequently, Mount Fee was one of the volcanoes in the Mount Cayley volcanic field illustrated by volcanologistJack Souther in 1980. Others included Mount Cayley,Cauldron Dome,Slag Hill, Ember Ridge andRing Mountain, which was titledCrucible Dome at the time. Souther created ageological map the following year that displayed the locations of the volcanoes and the regional terrain.[2]
Like other volcanoes in the Garibaldi Belt, Mount Fee is not monitored closely enough by the Geological Survey of Canada to ascertain how active itsmagma chamber is. This is partly because no major eruptions have taken place in Canada for over a hundred years and the volcano is located in a remote region. As a result, volcano monitoring is less important than dealing with other natural processes, such astsunamis,earthquakes andlandslides.[12] No recent earthquakes are known to have occurred at Mount Fee.[13] If it were to erupt there would likely be weeks, months or years of warning signs, such as clusters of minor earthquakes that would likely originate less than15 km (9.3 mi) below the surface. They are generally too small to be felt by people, but the existing network ofseismographs has been established to monitor tectonic earthquakes. However, the seismograph network is too far away to provide a good indication of what is happening under the mountain. It may sense an increase in seismic activity if the volcano becomes very restless, but this may only provide a warning for a significant eruption. It might detect activity only once the volcano has started erupting.[12] A significant eruption at Mount Fee would probably have considerable effects, particularly in a region like southwestern British Columbia where the Garibaldi Belt is located in a highly populated area.[4][12] Because of these concerns, significant support from Canadian university scientists has resulted in the construction of a baseline of knowledge on the state of the Garibaldi volcanoes.[12]
Based on theKöppen climate classification, Mt. Fee is located in themarine west coast climate zone of westernNorth America.[14] Mostweather fronts originate in thePacific Ocean, and travel east toward theCascade Range where they are forced upward by the range (Orographic lift), causing them to drop their moisture in the form of rain or snowfall. As a result, the Cascade Mountains experience high precipitation, especially during the winter months in the form of snowfall. Temperatures can drop below −20 °C with wind chill factors below −30 °C. The months July through September offer the most favorable weather for climbing Fee.
