The Navajo Section is a physiographic section of the larger

Colorado Plateau The Colorado Plateau, also known as the Colorado Plateau Province, is a physiographic and desert region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. This province covers an area of ...

s Province, which in turn is part of the larger

Intermontane Plateaus In the context of physical geography, the Intermontane Intermontane is a physiographic adjective formed from the prefix " inter-" (''signifying among, between, amid, during, within, mutual, reciprocal'') and the adjective "montane" (inhabiting ...

physiographic Division.

Geography

The Navajo Section is located in northeastern

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

and northwestern

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...

. It is named for the

Navajo Nation The Navajo Nation ( nv, Naabeehó Bináhásdzo), also known as Navajoland, is a Native American reservation in the United States. It occupies portions of northeastern Arizona, northwestern New Mexico, and southeastern Utah; at roughly , the ...

, with about half of the area of the section on the Navajo Reservation. The section is characterized by broad rolling plains on easily eroded and carved rocks, with

cuesta A cuesta (from Spanish ''cuesta'' "slope") is a hill or ridge with a gentle slope on one side, and a steep slope on the other. In geology the term is more specifically applied to a ridge where a harder sedimentary rock overlies a softer layer ...

s (ridges) and tablelands capped by gently dipping resistant

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

beds. One of the most prominent landform features of the Navajo Section is

Shiprock Shiprock ( nv, , "rock with wings" or "winged rock") is a monadnock rising nearly above the high-desert plain of the Navajo Nation in San Juan County, New Mexico, San Juan County, New Mexico, United States. Its peak elevation is above sea le ...

, a

monadnock An inselberg or monadnock () is an isolated rock hill, knob, ridge, or small mountain that rises abruptly from a gently sloping or virtually level surrounding plain. In Southern Africa a similar formation of granite is known as a koppie, a ...

formation near the town of Shiprock, New Mexico.

Elevations

The lowest point in the Navajo Section is about , near the

Four Corners The Four Corners is a region of the Southwestern United States consisting of the southwestern corner of Colorado, southeastern corner of Utah, northeastern corner of Arizona, and northwestern corner of New Mexico. The Four Corners area ...

area. The boundary between this section and the Canyon Lands Section is nearby, in the San Juan River basin. The highest point of the Navajo Section is at Chromo Mountain on the

Continental Divide A continental divide is a drainage divide on a continent such that the drainage basin on one side of the divide feeds into one ocean or sea, and the basin on the other side either feeds into a different ocean or sea, or else is endorheic, not ...

near Chama, New Mexico.

Adjacent

Adjacent to the Navajo Section are the: # Canyon Lands Section to the north. #

Rio Grande rift The Rio Grande rift is a north-trending continental rift zone. It separates the Colorado Plateau in the west from the interior of the North American craton on the east. The rift extends from central Colorado in the north to the state of Chihua ...

of the

Basin and Range Province The Basin and Range Province is a vast physiographic region covering much of the inland Western United States and northwestern Mexico. It is defined by unique basin and range topography, characterized by abrupt changes in elevation, alternating ...

to the east. # Acoma-Zuni Section to the south. # Grand Canyon Section to the west

Geology and physiography

The area is predominantly generally horizontal

beds with some

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...

sequences of late

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

and early

Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...

age. A few areas of the section also have abundant volcanic necks and

buttes __NOTOC__ In geomorphology, a butte () is an isolated hill with steep, often vertical sides and a small, relatively flat top; buttes are smaller landforms than mesas, plateaus, and tablelands. The word ''butte'' comes from a French word mea ...

, but due to the arid weather and soft sandstone, many of the rock formations of the area have eroded to form distinctive features of long

s, shallow canyons and valleys, narrow fan terraces, undulating plateaus, isolated

mesas A mesa is an isolated, flat-topped elevation, ridge or hill, which is bounded from all sides by steep escarpments and stands distinctly above a surrounding plain. Mesas characteristically consist of flat-lying soft sedimentary rocks capped by a ...

, steep hills, and some shale

badlands Badlands are a type of dry terrain where softer sedimentary rocks and clay-rich soils have been extensively eroded."Badlands" in ''Chambers's Encyclopædia''. London: George Newnes, 1961, Vol. 2, p. 47. They are characterized by steep slopes, m ...

. ;San Juan Basin Near the Four Corners area is a steeply tilted

monocline A monocline (or, rarely, a monoform) is a step-like fold in rock strata consisting of a zone of steeper dip within an otherwise horizontal or gently-dipping sequence. Formation Monoclines may be formed in several different ways (see diagram) * ...

known as The Hogback, which trends southwestward from where the San Juan River enters the area. Here the San Juan River flows into an area known as the

San Juan Basin The San Juan Basin is a geologic structural basin located near the Four Corners region of the Southwestern United States. The basin covers 7,500 square miles and resides in northwestern New Mexico, southwestern Colorado, and parts of Utah a ...

, where the western San Juan Basin is typified by exposures of the Fruitland and Menefee Formations. A stepped sequence of high stream terraces, present above the San Juan River and its tributaries, represents abandoned

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

flood plains.

References

External links