Meteor Crater, AZ | GeologyVirtualTrips

METEOR (BARRINGER) CRATER

FIELD TRIP STOP – PERHAPS THE BEST-PRESERVED METEOR IMPACT CRATER ON EARTH

LOCATION: Meteor Crater is found about 37 miles east of Flagstaff, AZ, just south of I-40.

GEOLOGIC FEATURES: Meteor Impact Crater.

DESCRIPTION: Meteor Crater, also named after Daniel Barringer who first suggested an origin by meteor impact, has a diameter of 3900-4100 ft. and a depth of about 570 ft. Its rim rises between 120-200 ft above the surrounding landscape. Since the impact, the crater is thought to have lost 20 ft of rim elevation, with the crater bottom having been filled with about 200-250 ft. of rubble and sand, including 90 ft. of lake deposits.

Impact is thought to have occurred about 50,000 years ago by a 150 ft wide meteor weighing 300,000 tons traveling at a speed somewhere between 8 - 12 miles/sec.

The meteorite was composed of Iron and Nickel. Most of it vaporized on impact leaving behind tiny metal spheroids. An estimated 30 tons of large fragments are scattered around the crater.

Besides meteorite fragments, other evidence of meteor impact include rock layers thrown upward to form the crater rim, rocks deformed by temperature and pressure, and various types of shock metamorphism. Rock layers that form the rim, having been uplifted by impact, slope away from the crater center. Strata are mainly composed of the Permian Coconino Sandstone, Toroweap Fm., and Kaibab Limestone, as well as the Triassic Moenkopi Fm. though only the latter two rock formations are prominently exposed within the crater. Interestingly, the Permian strata exposed here (Coconino, Toroweap, and Kaibab) are the same that cap the Grand Canyon. The Moenkopi Fm. is the same rock that lies just above the Kaibab just outside the Grand Canyon boundary.

STUDENT QUESTIONS:

(1) Craters created by meteorite impact have occurred since the Earth was formed. Why is Meteor Crater in Arizona thought to be the best preserved in the world?

(2) Describe the sequence of events likely to occur at Meteor Crater in the geologic future.

(3) How does the estimated size of the meteor compare to the size of the crater itself?

(4) CHALLENGE: Looking at known meteorite craters exposed around the world, how do their sizes relate to the estimated size of the meteorite creating them? Is their a relationship between the two?

(5) CHALLENGE: Provide several examples of Shock Metamorphism identified at Meteor Crater that were used to verify meteor impact craters around the world.

SELECTED REFERENCES:

-King, David (2017). Guidebook to the Geology of Barringer Meteorite Crater, Arizona (a.k.a. Meteor Crater) (2nd ed.). LPI Contribution No. 2040. Lunar and Planetary Institute: Accessed on Feb 28, 2020:

https://www.lpi.usra.edu/publications/books/barringer_crater_guidebook/

-Tobin, James. Meteor Crater Arizona. The Meteorite Exchange. Accessed on Feb. 28, 2020: https://www.meteorite.com/meteor-crater/

VIDEO: Meteor Crater (https://youtu.be/0vt4eq0_u3E)

PHOTOS:

Figure 1 - A panoramic view of the crater looking towards the south..

Figure 2 - View to the south (east is to the left, west is to the right). Crater walls not covered by talus are mainly of the Permian Kaibab Limestone and overlying Triassic Moenkopi Sandstone.

Figure 3 - The eastern wall of the crater. Solid rock exposures are of the Permian Kaibab Limestone.

Figure 4 - The central area of the crater is composed of Quaternary Lake and Playa layers.

Figure 5 - Looking to the southwest. In the bottom left (near the crater center) are remnants of drillholes and shafts contructed by Daniel Barringer along with an American Flag and cutout of an astronaut representing the use of the Crater by astronauts of the Apollo program.

Figure 6 - The western wall of the crater. Rock strata are of the Permian Kaibab Limestone and overlying Moenkopi Sandstone and Shale (see Shoemaker's stratigraphic cross-section in the figure below).

Figure 7 - Western to northern wall of crater rim.

Figure 8 - Note the strata (seen best on the right) dipping away from the center of the crater.

Figure 9 - Closer view of southeastern wall showing the exposure of the Kaibab Limestone.

Figure 10 - Closer view of Figure 9. Kaibab Limestone.

Figure 11 - Closer view of Figure 10.

Figure 12 - Close-up of southwest crater wall.

Figure 13 - Close-up of west crater wall with exposure of the Kaibab and Toroweap Formations. See Shoemaker's cross-section on Figure 15.

Figure 14 - On the crater floor can be seen a 3 x 5 ft American flag (same size as planted on the moon) and a cutout of a 6 ft. tall astronaut. Between 1963 and 1970, American astronauts trained in Meteor Crater due to its similarity to a lunar landscape. The crater floor also has a number of drill holes and shafts created by Daniel Barringer in his failed attempt to find the remains of the original large iron meteorite.

Figure 15 - Geology of Meteor Crater as constructed by Eugene Shoemaker. Note the prominent exposure of the Permian Kaibab Limestone (Pk) on the east wall of the crater, and the Kaibab and Triassic Moenkopi (Rm) on the west wall.

Figure 16 - About 3 ft across, the Holsinger Meteorite weighs 1412 lbs. This meteorite is on display at the Visitor's Center / Discovery Center at Meteor Crater.

Figure 17 - The Moenkopi red sandstone and shale lies above the Kaibab Limestone and is viewed here along the crater rim, just east of the Museum and Visitor's Center.

Figure 18 - From a distance, Meteor Crater looks like any ordinary low-lying hill. This photo was taken on the road leading from I-40 to the crater.