Hopi Buttes volcanic field
Encyclopedia
Monogenetic volcanic field
A monogenetic volcanic field is a volcanic field of small, scattered volcanic vents. These volcanic fields, containing numerous monogenetic volcanoes, are noted for having only one short eruptive event at each volcano, as opposed to regular volcanoes that have several eruptions from the same vent...
volcanic field
Volcanic field
A volcanic field is an area of the Earth's crust that is prone to localized volcanic activity. They usually contain 10 to 100 volcanoes, such as cinder cones and are usually in clusters. Lava flows may also occur...
located on the Colorado Plateau
Colorado Plateau
The Colorado Plateau, also called the Colorado Plateau Province, is a physiographic region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. The province covers an area of 337,000 km2 within western Colorado, northwestern New Mexico,...
mostly on the Navajo Reservation around the town of Dilkin
Dilkon, Arizona
Dilkon is a census-designated place in Navajo County, Arizona, United States. The population was 1,265 at the 2000 census. The name of the town is said to be derived from the Navajo phrase "smooth black rock" or "bare surface".- Government :...
in northeastern Arizona north of Holbrook
Holbrook
-Places:Australia*Holbrook, New South WalesEngland*Holbrook, Derbyshire*Holbrook, Somerset*Holbrook, South Yorkshire*Holbrook, Suffolk*Holbrook, Horsham, West SussexUnited States*Holbrook, Arizona*Holbrook, Idaho*Holbrook, Massachusetts...
.
The volcanic field covers an area of aproximatly 965 square miles (2,499.3 km²) and contains about 300 maar
Maar
A maar is a broad, low-relief volcanic crater that is caused by a phreatomagmatic eruption, an explosion caused by groundwater coming into contact with hot lava or magma. A maar characteristically fills with water to form a relatively shallow crater lake. The name comes from the local Moselle...
s and diatreme
Diatreme
A diatreme is a breccia-filled volcanic pipe that was formed by a gaseous explosion. Diatremes often breach the surface and produce a tuff cone, a filled relatively shallow crater known as a maar, or other volcanic pipes.- Word origin :...
s.
The erosional exposure of the deposits varies with those in the eastern portion exhibiting the shallowly eroded maar deposits and those in the western portion the more deeply eroded feeder diatremes. The maars result from explosive interaction of the hot diatreme material with the groundwater system and result in a mixture of volcanic tuff
Tuff
Tuff is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption. Tuff is sometimes called tufa, particularly when used as construction material, although tufa also refers to a quite different rock. Rock that contains greater than 50% tuff is considered...
material and sediments of the Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
–Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
lacustrine
Lacustrine
Lacustrine means "of a lake" or "relating to a lake".Specifically, it may refer to:*Lacustrine plain*Lacustrine delta-Fish:*Lacustrine goby , a type of small fish found in Philippine waters belonging to the Gobiidae family, known in Tagalog as dulong-See also:*Fluvial - of or relating a...
sediments of the Bidahochi Formation. In the western protion of the field the buttes consist of the feeder diatremes of monchiquite and nepheline syenite
Nepheline syenite
Nephelene syenite is a holocrystalline plutonic rock that consists largely of nepheline and alkali feldspar. The rocks are mostly pale colored, grey or pink, and in general appearance they are not unlike granites, but dark green varieties are also known...
magma
Magma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...
s.
Most of the volcanic activity occurred between 8.5 and 6 million years ago, with the most recent dated at 4.2 million years ago.
Notable vents
| Name | Elevation | Location | Last eruption | |
| meters | feet | Coordinates | ||
| Coliseum Maar | 1,811 | 5,940 | 35°24′N 110°06′W | |
| Morale Claim Maar | 1,859 | 6,100 | 35°30′N 111°00′W | |
