Arcadia quadrangle

Arcadia quadrangle

Map of Arcadia quadrangle from Mars Orbiter Laser Altimeter (MOLA) data. The highest elevations are red and the lowest are blue.
Coordinates	47°30′N 90°00′W / 47.5°N 90°W / 47.5; -90Coordinates: 47°30′N 90°00′W / 47.5°N 90°W / 47.5; -90

The Arcadia quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The quadrangle is located in the north-central portion of Mars’ western hemisphere and covers 240° to 300° east longitude (60° to 120° west longitude) and 30° to 65° north latitude. The quadrangle uses a Lambert conformal conic projection at a nominal scale of 1:5,000,000 (1:5M). The Arcadia quadrangle is also referred to as MC-3 (Mars Chart-3).

The southern and northern borders of the Arcadia quadrangle are approximately 3,065 km and 1,500 km wide, respectively. The north to south distance is about 2,050 km (slightly less than the length of Greenland). The quadrangle covers an approximate area of 4.9 million square km, or a little over 3% of Mars’ surface area. The region called Tempe Terra is in the Arcadia quadrangle.

Several features found in this quadrangle are interesting, especially gullies which are believed to be caused by relatively recent flows of liquid water. Dark slope streaks and dust devil tracks can have a striking appearance.

Arcadia is the name of a telescopic albedo feature located at 45° north latitude (N) and 260° east longitude (E) on Mars. The feature was named after a mountainous region in southern Greece. The name was approved by the International Astronomical Union(IAU) in 1958.

The quadrangle contains Alba Patera, the largest volcano (by area and volume) in the solar system and Tempe Terra, a highly fractured block of ancient crust about the size of Alaska.

Large troughs (long narrow depressions) are called fossae in the geographical language used for Mars. This term is derived from Latin; therefore fossa is singular and fossae are plural. These troughs form when the crust is stretched until it breaks. The stretching can be due to the large weight of a nearby volcano. Fossae/pit craters are common near volcanoes in the Tharsis and Elysium system of volcanoes. A trough often has two breaks with a middle section moving down, leaving steep cliffs along the sides; such a trough is called a graben.Lake George, in northern New York State, is a lake that sits in a graben. Pit craters are often associated with graben. Pit craters do not have rims or ejecta around them, like impact craters do. Studies have found that on Mars a fault may be as deep as 5 km, that is the break in the rock goes down to 5 km. Moreover, the crack or fault sometimes widens or dilates. This widening causes a void to form with a relatively high volume. When surface material slides into the void, a pit crater or a pit crater chain forms. On Mars, individual pit craters can join to form chains or even to form troughs that are sometimes scalloped. Other ideas have been suggested for the formation of fossae and pit craters. There is evidence that they are associated with dikes of magma. Magma might move along, under the surface, breaking the rock and more importantly melting ice. The resulting action would cause a crack to form at the surface. Pit craters are not common on Earth. Sinkholes, where the ground falls into a hole (sometimes in the middle of a town) resemble pit craters on Mars. However, on the Earth these holes are caused by limestone being dissolved thereby causing a void.