Editing Flagstaff, Arizona (section)

===Geology and topography===
{{main|Astrogeology Research Program|Colorado Plateau#Geology|Geology of the Grand Canyon area|San Francisco volcanic field}}
[[File:Grand-canyon-stones.jpg|thumb|upright|Local rock [[Stratum|strata]] monument in Heritage Square of downtown Flagstaff|alt=Rock sculpture]]

Flagstaff lies on the southern edge of the Colorado Plateau, and is largely [[limestone]] under [[San Francisco volcanic field]]. The oldest rock types of the area are part of North America's original crust, [[Precambrian]] [[granite]] and [[schist]] from 1.7 to 1.8 billion years ago. On top of this is [[Paleozoic]] [[sandstone]], limestone, [[shale]] and [[siltstone]] deposited on what was then (544 to 248 million years ago) different surfaces, including a shallow seabed, muddy land, and sandy desert. The rock layers from this period are (bottom to top): [[Tapeats Sandstone]], [[Bright Angel Shale]] and [[Muav Limestone]], [[Martin Formation]], [[Redwall Limestone]], [[Supai Group]], [[Coconino Sandstone]], [[Toroweap Formation]], and [[Kaibab Limestone]]. The last three of these are still exposed. On top of the Paleozoic rock is [[Mesozoic]] Moenkopi Formation, from 248 to 65 million years ago. Other Mesozoic layers formed on top of this, but were eroded away. In the Flagstaff area, layers of rock from the Paleozoic and Mesozoic eras accumulated up to {{convert|10000|ft|m}} deep, but most of this was eroded.<ref name=":23">{{Cite book|last=Bezy|first=John V.|url=https://friendsoftheriodeflag.org/wp-content/uploads/2015/12/Bezy-J.V.-2003-A-guide-to-the-geologt-of-the-Flagstaff-area.-Arizona-Geological-Survey.pdf|title=A guide to the geology of the Flagstaff area|publisher=Arizona Geological Survey|year=2003|isbn=1892001179|location=Tucson, AZ|oclc=53701547|access-date=April 8, 2020|archive-date=September 23, 2020|archive-url=https://web.archive.org/web/20200923192035/https://friendsoftheriodeflag.org/wp-content/uploads/2015/12/Bezy-J.V.-2003-A-guide-to-the-geologt-of-the-Flagstaff-area.-Arizona-Geological-Survey.pdf|url-status=live}}</ref> A soft basalt layer covers some of the rock at the surface.<ref name=":23" /><ref>{{Cite web|url=http://www2.nau.edu/~gaud/RiodeFlag/rdf_geology.htm|title=Rio de Flag: Geology|website=www2.nau.edu|access-date=April 8, 2020|archive-date=November 30, 2020|archive-url=https://web.archive.org/web/20201130134022/http://www2.nau.edu/~gaud/RiodeFlag/rdf_geology.htm|url-status=live}}</ref>

Moenkopi Formation red sandstone is a distinctive feature of Flagstaff, as it was used as a building material from the 1880s because of its fire retardant properties. The source used for quarrying most of this rock was a deposit 1 mile east of the town, which fell under the control of Charles Begg in 1887, who then began selling the stone across the southwest – after he made a successful sale in California that expanded the business, he was replaced in 1888 by a master quarryman. While it was used as building material across the West, some of Flagstaff's most prominent buildings are famous for the stone, including the Bank Hotel,<ref name=":2" /> Weatherford Hotel, Babbitt Brothers Building, Coconino County Courthouse,<ref name="themetown2" /> and various NAU buildings, including Old Main.<ref name=":2" />

In the [[Laramide orogeny]], which began about 65–75 million years ago, the [[Western United States]] underwent stress in rock formation; in the [[Four Corners]] region this pushed up the preexisting layers and ultimately formed the Colorado Plateau (and the [[Rocky Mountains]]). Around Flagstaff more specifically, this process deformed flat rock layers into folds, and allowed surface rivers to cut deep canyons in the younger rock layers. From about 25 million years ago, more [[Fault (geology)|faults]] were broken again in Flagstaff, and volcanic activity began about 6 million years ago with [[magma]] flowing up these faults to create [[Lava|lava flows]]. [[Types of volcanic eruptions|Eruptions]] occurred between 3 million and 1,000 years ago, affecting the Paleozoic and Mesozoic rocks. The city's Mount Elden is a [[lava dome]] made of [[dacite]], Sunset Crater is the youngest feature of the San Francisco volcanic field and formed in the last 1,000 years by an [[explosive eruption]], while S P Crater was formed between 75,000 and 70,000 years ago by piles of [[lapilli]] and [[volcanic bombs]] spouting from a [[lava lake]].<ref name=":23" />

In the 1960s, the geology and topography of the Flagstaff area, including formations like Meteor Crater, was seen as similar to environments that would be encountered on the Moon in terms of [[planetary geology]]. The [[Astrogeology Research Program]] was therefore moved to Flagstaff in 1962, with the program completing in 1963, to train astronauts.<ref name="Rocky Moon 1993">{{cite web|url=http://www.lpi.usra.edu/publications/books/rockyMoon/|title=To a Rocky Moon: A Geologist's History of Lunar Exploration|last=Wilhelms|first=Don|date=1993|access-date=April 9, 2020|archive-date=November 7, 2015|archive-url=https://web.archive.org/web/20151107065945/http://www.lpi.usra.edu/publications/books/rockyMoon/|url-status=live}}</ref><ref>{{Citation|last1=Vaughan|first1=R. Greg|title=Walk in the footsteps of the Apollo astronauts: A field guide to northern Arizona astronaut training sites|date=2019|url=https://pubs.geoscienceworld.org/books/book/2196/chapter/122801792|work=Geologic Excursions in Southwestern North America|publisher=Geological Society of America|language=en|doi=10.1130/2019.0055(12)|isbn=978-0813756554|access-date=April 9, 2020|last2=Schindler|first2=Kevin|last3=Stevens|first3=Jeanne|last4=Hough|first4=Ian|s2cid=211649702|archive-date=February 13, 2023|archive-url=https://web.archive.org/web/20230213103721/https://pubs.geoscienceworld.org/books/book/2196/chapter/122801792|url-status=live}}</ref>