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Geological Destination - Ship Rock

Nearby to Four Corners Monument, and actually used during the original survey of the monument, is the monumental geological feature of Ship Rock. It is located in northwestern New Mexico, near the town of Ship Rock on the Navajo Nation. It is also known as Tsé Bit'a'í, or "the winged rock" in the native Navajo language.

View of Ship Rock from the south

Ship Rock is the volcanic remnant, or volcanic neck, of a prehistoric volcano that erupted ~30 million years ago. Ship Rock intruded within the much older Mancos Shale, a Cretaceous age (~90 million years old) formation made up of mostly claystone and siltstone with minimal amounts of sandstone and limestone that formed on the bottom of the Interior Cretaceous Seaway that once dominated the central portion of North America.

Geological map of Ship Rock, NM. Image courtesy of the NGMDB.
Part of the Navajo Volcanic Field, Ship Rock formed as what is known as a diatreme, a volcanic vent or pipe that was forced through flat-lying sedimentary rocks producing an expanded vent through explosive energy. The main portion of Ship Rock is composed of volcanic breccia, made up of a type of potassium-rich volcanic rock called "minette", which is thought to be formed from melting of the mantle. Ship Rock itself is ~1,600 feet wide at its widest and ~1,600 feet tall. When the volcano intruded into the Mancos Shale, it is thought that the current visible features were solidified ~2,500 to 3,300 feet below the surface of the Earth. However, the extreme weakness of the Mancos Shale has allowed extensive erosion to occur, carrying away the shale while leaving behind the much harder volcanic rock.
View of Ship Rock from the south and the southern dike.
One of the more notable features of Ship Rock are the radiating features that emanate from the pinnacle itself. These were formed as volcanic features known as dikes. Dikes are vertical intrusions of magma into a surrounding bedrock. The vertical intrusion then hardens, leaving behind sheets of lava rock. Radiating outward from Ship Rock are six different dikes. These dikes can be seen on the geologic map above as red lines. However, due to the size of the southern dike and the distance to Ship Rock, I was only able to get a picture of the main southern dike.
View of the southern Ship Rock dike facing towards the south, away from Ship Rock.
View of the southern dike, facing towards the north, at Ship Rock
Closer up view of the southern dike.
It should be noted that Ship Rock is considered sacred to the Navajo, and while viewing the rock is allowed, climbing and hiking on the rock are prohibited.

A bit more of a distant view of Ship Rock. The two points on the right side of the photo are remnants of two of the smaller dikes that radiate out towards the northeast from Ship Rock.
References
https://ngmdb.usgs.gov/mapview/?center=-108.755,36.663&zoom=12
https://geoinfo.nmt.edu/tour/landmarks/shiprock/home.html https://www.nps.gov/articles/diatremes-and-maars.htm http://volcano.oregonstate.edu/navajo-volcanic-field

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