Mount Jefferson (Montana)
Encyclopedia
Mount Jefferson is a mountain
in the U.S. state
of Montana
, and is one of the many 10,000+ ft peaks in the Tobacco Root Mountains
. The mountain is located in Beaverhead-Deerlodge National Forest
. (There is also another Mount Jefferson in Montana, further south, on the Idaho/Montana border.) Hollowtop Mountain is an adjacent, taller peak less than .75 miles (1.2 km) to the north. Over the years, the two summits have had numerous names and altitudes recorded on various maps. According to U.S. Geological Survey topographic maps, Mount Jefferson is 10513 ft (3,204 m), while Hollowtop Mountain to the north is 10604 ft (3,232 m).
Some earlier, published maps labeled the northern peak as Mt. Jefferson. Confusion may arise from the fact that the horizontal triangulation control station (VABM) named JEFFERSON is located on the southern peak, and this designation is found on many maps.
In 1933, Tansley and others referred to the high point of the range as Mt. Jefferson, at 10,600 ft. The northern peak was labeled Mt. Jefferson on the Gallatin National Forest
map of 1937, with an erroneous (but long-perpetuated) elevation of 10,740’ given. The southern peak was called Hollow Top Mountain, at 10,513’. The next year, 1938, the Deerlodge National Forest map dodged the issue: the northern peak received two designations — Hollowtop Mtn. and Mt. Jefferson. The southern peak was labeled with the JEFFERSON control station only.
Reid in 1957 mapped the northern peak as Mt. Jefferson and the southern one as Goat Mountain. In 1960, the Waterloo 15-minute topographic quad showed Mt. Jefferson, to the north, at 10,604’, and the southern one as Hollowtop Mtn (10,513’) with the JEFFERSON control station label. In 1976, the U.S. Board on Geographic Names stated that this was the correct designation.
The 1962 Dillon Quad (1:250,000) labeled the northern peak Hollow Top Mt., and the other one had no designation other than the triangular control station mark. The 1963 Beaverhead National Forest map shows Mt. Jefferson to the north at 10,604’ and the JEFFERSON control station to the south at 10,740’, while the 1970 Deerlodge National Forest map is similar, but with the name Hollowtop Mtn. and no elevation for the southern peak.
Oil Company highway maps from the late 1960s and early 1970s show Hollowtop Mtn. at 10,740’, while the Official Montana Highway Map, from at least 1971 onwards, has Hollow Top Mtn. at 10,604’. As recently as 1976, the Beaverhead National Forest map showed Mt. Jefferson to the north (10,604’) and Hollowtop Mtn. with the JEFFERSON control station to the south.
In 1987, the Interagency Visitors Map of Southwest Montana (produced by the Forest Service, USGS, and State of Montana) shows the northern peak labeled Hollowtop Mtn. (10,604’), and the southern peak is marked Mt. Jefferson and includes the control station label. This is the first map known that shows both names, with Hollowtop north of Mt. Jefferson.
Finally, the 1989 7½-minute quad (Noble Peak) also shows Hollowtop Mountain (10,604’) to the north, with Mt. Jefferson (10,513’) to the south with the control station. Numerous hand-held GPS measurements indicate that these listed elevations are probably accurate.
Apparently no peak has an elevation of 10,740’, and all sources agree that the JEFFERSON triangulation station is on the southern peak. Decades of use would have “Hollowtop” to the north, and perhaps the newer maps reflect this usage. The northern peak is labeled “Hollowtop” and “Hollow Top” on various maps, with a single word somewhat more common.
, a body of granite
intruded about 75 million years ago during the Late Cretaceous
Period. The Tobacco Root Batholith is often called a satellite of the much larger Boulder Batholith
. Parts of Mt. Jefferson-Hollowtop contain Archean
metamorphic rocks. Intrusion of the batholith produced considerable mineralization along northwest-trending faults. The Mammoth Mine, north of Mt. Jefferson-Hollowtop produced more than $2,000,000 in gold over its life (mostly in the 1880s-1910s). The Nicholson Gold Mine, on the west flank of Mt. Jefferson, has been active as recently as the middle 1990s, but no production has been reported. The area of the mine is private property, a patented mining claim.
The bowl-like crest of Hollowtop, best viewed from the towns of Pony, Montana
and Harrison, Montana
to the east, is not a classical glacial cirque
. Snow and perhaps ice certainly accumulated there during the ice age
, but scouring typical of a moving glacier
is not evident.
Mountain
Image:Himalaya_annotated.jpg|thumb|right|The Himalayan mountain range with Mount Everestrect 58 14 160 49 Chomo Lonzorect 200 28 335 52 Makalurect 378 24 566 45 Mount Everestrect 188 581 920 656 Tibetan Plateaurect 250 406 340 427 Rong River...
in the U.S. state
U.S. state
A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...
of Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
, and is one of the many 10,000+ ft peaks in the Tobacco Root Mountains
Tobacco Root Mountains
The Tobacco Root Mountains lie in the northern Rocky Mountains, between the Jefferson and Madison Rivers in southwest Montana. The highest peak is Hollowtop at...
. The mountain is located in Beaverhead-Deerlodge National Forest
Beaverhead-Deerlodge National Forest
The Beaverhead-Deerlodge National Forest is the largest of the National Forests in Montana, United States. Covering , the forest is broken into nine separate sections and stretches across eight counties in the southwestern area of the state. President Theodore Roosevelt named the two forests in...
. (There is also another Mount Jefferson in Montana, further south, on the Idaho/Montana border.) Hollowtop Mountain is an adjacent, taller peak less than .75 miles (1.2 km) to the north. Over the years, the two summits have had numerous names and altitudes recorded on various maps. According to U.S. Geological Survey topographic maps, Mount Jefferson is 10513 ft (3,204 m), while Hollowtop Mountain to the north is 10604 ft (3,232 m).
Nomenclature
Nomenclature for Mount Jefferson has seen considerable change and confusion over the years. A.N. Winchell, in his 1914 report, Mining Districts of the Dillon Quadrangle, referred to the highest peak in the Tobacco Roots as “Jefferson Peak, locally called Old Hollowtop.” Since that time the more northerly, and higher, of two adjacent peaks has usually been called Hollowtop. This naming convention is easily explained upon viewing the dish-shaped northeasterly-trending glacial cirque that occupies the top of Hollowtop peak. Information is scanty before 1914. Peale (1896) referred to Ward Peak, near Pony, and “unnamed high peaks” in the range. Present local terminology places Ward Peak further south, near McAlister. The idea that Lewis and Clark named the ranges along with the rivers cannot be confirmed.Some earlier, published maps labeled the northern peak as Mt. Jefferson. Confusion may arise from the fact that the horizontal triangulation control station (VABM) named JEFFERSON is located on the southern peak, and this designation is found on many maps.
In 1933, Tansley and others referred to the high point of the range as Mt. Jefferson, at 10,600 ft. The northern peak was labeled Mt. Jefferson on the Gallatin National Forest
Gallatin National Forest
Founded in 1899, Gallatin National Forest is located in south central Montana, United States. The forest comprises 2.1 million acres and has portions of both the Absaroka-Beartooth and Lee Metcalf Wilderness areas within its boundaries...
map of 1937, with an erroneous (but long-perpetuated) elevation of 10,740’ given. The southern peak was called Hollow Top Mountain, at 10,513’. The next year, 1938, the Deerlodge National Forest map dodged the issue: the northern peak received two designations — Hollowtop Mtn. and Mt. Jefferson. The southern peak was labeled with the JEFFERSON control station only.
Reid in 1957 mapped the northern peak as Mt. Jefferson and the southern one as Goat Mountain. In 1960, the Waterloo 15-minute topographic quad showed Mt. Jefferson, to the north, at 10,604’, and the southern one as Hollowtop Mtn (10,513’) with the JEFFERSON control station label. In 1976, the U.S. Board on Geographic Names stated that this was the correct designation.
The 1962 Dillon Quad (1:250,000) labeled the northern peak Hollow Top Mt., and the other one had no designation other than the triangular control station mark. The 1963 Beaverhead National Forest map shows Mt. Jefferson to the north at 10,604’ and the JEFFERSON control station to the south at 10,740’, while the 1970 Deerlodge National Forest map is similar, but with the name Hollowtop Mtn. and no elevation for the southern peak.
Oil Company highway maps from the late 1960s and early 1970s show Hollowtop Mtn. at 10,740’, while the Official Montana Highway Map, from at least 1971 onwards, has Hollow Top Mtn. at 10,604’. As recently as 1976, the Beaverhead National Forest map showed Mt. Jefferson to the north (10,604’) and Hollowtop Mtn. with the JEFFERSON control station to the south.
In 1987, the Interagency Visitors Map of Southwest Montana (produced by the Forest Service, USGS, and State of Montana) shows the northern peak labeled Hollowtop Mtn. (10,604’), and the southern peak is marked Mt. Jefferson and includes the control station label. This is the first map known that shows both names, with Hollowtop north of Mt. Jefferson.
Finally, the 1989 7½-minute quad (Noble Peak) also shows Hollowtop Mountain (10,604’) to the north, with Mt. Jefferson (10,513’) to the south with the control station. Numerous hand-held GPS measurements indicate that these listed elevations are probably accurate.
Apparently no peak has an elevation of 10,740’, and all sources agree that the JEFFERSON triangulation station is on the southern peak. Decades of use would have “Hollowtop” to the north, and perhaps the newer maps reflect this usage. The northern peak is labeled “Hollowtop” and “Hollow Top” on various maps, with a single word somewhat more common.
Geology
Most of the mountain is underlain by the Tobacco Root BatholithBatholith
A batholith is a large emplacement of igneous intrusive rock that forms from cooled magma deep in the Earth's crust...
, a body of granite
Granite
Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...
intruded about 75 million years ago during the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
Period. The Tobacco Root Batholith is often called a satellite of the much larger Boulder Batholith
Boulder Batholith
The Boulder Batholith is a small batholith in southwest Montana, exposed at the surface as granite and serving as the host rock for rich mineralized deposits at Butte, Montana and other locations....
. Parts of Mt. Jefferson-Hollowtop contain Archean
Archean
The Archean , also spelled Archeozoic or Archæozoic) is a geologic eon before the Paleoproterozoic Era of the Proterozoic Eon, before 2.5 Ga ago. Instead of being based on stratigraphy, this date is defined chronometrically...
metamorphic rocks. Intrusion of the batholith produced considerable mineralization along northwest-trending faults. The Mammoth Mine, north of Mt. Jefferson-Hollowtop produced more than $2,000,000 in gold over its life (mostly in the 1880s-1910s). The Nicholson Gold Mine, on the west flank of Mt. Jefferson, has been active as recently as the middle 1990s, but no production has been reported. The area of the mine is private property, a patented mining claim.
The bowl-like crest of Hollowtop, best viewed from the towns of Pony, Montana
Pony, Montana
Pony is an unincorporated community in northeastern Madison County, Montana, United States on the eastern edge of the Tobacco Root Mountains.In the late nineteenth century, Pony was a prosperous gold-mining community with at least 5,000 residents. A number of historic buildings from Pony's boom era...
and Harrison, Montana
Harrison, Montana
Harrison is a census-designated place in Madison County, Montana, United States. The population was 162 at the 2000 census.-Geography:Harrison is located at ....
to the east, is not a classical glacial cirque
Cirque (landform)
thumb|250 px|Two cirques with semi-permanent snowpatches in [[Abisko National Park]], [[Sweden]].A cirque or corrie is an amphitheatre-like valley head, formed at the head of a valley glacier by erosion...
. Snow and perhaps ice certainly accumulated there during the ice age
Ice age
An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...
, but scouring typical of a moving glacier
Glacier
A glacier is a large persistent body of ice that forms where the accumulation of snow exceeds its ablation over many years, often centuries. At least 0.1 km² in area and 50 m thick, but often much larger, a glacier slowly deforms and flows due to stresses induced by its weight...
is not evident.