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Amboy Crater Earthcache EarthCache

Hidden : 11/13/2007
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Geocache Description:

Amboy Crater is approximately equidistant (about 75 miles either way) between Needles, CA and Barstow, CA. This is one of the more interesting sections of Route 66! Come to Amboy Crater and "Get Your Kicks!"

Amboy Crater, formed of ash and cinders, is 250 feet high and 1,500 feet in diameter. It is situated in one of the youngest volcanic fields in the United States. It is located in the Barstow-Bristol trough, a conspicuous west-northwest trending physiographic feature which approximately straddles the boundary between the Mojave and Sonoran tectonic blocks.

This field was created by at least 4 distinct periods of eruptions, resulting in a coaxially nested group of volcanic cinder cones. The most recent eruption of Amboy Crater was approximately 10,000 years ago.

The lava flows consist of basalt rich in minerals of magnesium, iron, and calcium. Upon close examination, you may be able to see minute green-colored olivine crystals. The red color indicates the presence of ferric iron and is a result of steam on heated rocks.

Trail to the Crater: The Park Rangers tell us to allow yourself a minimum of 3 hours hiking time (my family was able to do it in 2 hours). Located 1.1 miles from the day use area, the cone is one-mile in circumference. Round trip is roughly 3 miles. Follow the trail to the west of the cinder cone. This will take you to a wide opening where an explosive eruption had breached the crater wall. From here, the climb to the top is and 80-foot incline. Due to extreme heat, it is suggested that hikes be planned between the months of October thru April.

Scenic Overview: Located at
N 34.33.372
W 115.46.858
This covered platform is ADA compliant and provides for wonderful viewing of the crater with a shaded area.

LEAVE NO TRACE: Enjoy your visit and help minimize impacts by staying on designated routes to reduce erosion, packing out litter, respecting others, and leaving natural and cultural resources as you find them.

Amenities: There are several covered picnic benches in the public parking lot. Facilities at the crater consist of a day use area with four shaded picnic tables, two vault toilets, and a shaded scenic overlook. The facilities are connected by a series of concrete walkways and are all wheel-chair accessible. The closest facilities for food and gas are either in Ludlow, CA 30 miles to the west or Fenner, CA 42 miles to the east. There is no water available on site, so please plan accordingly.

For more information:

Amboy Crater is a good place to observe various volcanic features. Look for the following when you are exploring the area:

"PAHOEHOE FLOW" is a molten material that contained steam, making it flow more smoothly, creating a surface like rope with a glassy outer skin.

"JUMBLES" are subsurface explosions that disrupted hardened lave flows, creating chunks of volcanic rock.

"BOWL-SHAPED DEPRESSIONS" were formed as a result of inflation of an emplaced, but still plastic, curst by molten lava around a general void in the flow. There are twelve depressions throughout the lava field, ranging from 25 to 300 feet in diameter and 4 to 40 feet in depth.

"PRESSURE RIDGES" are long, narrow ridges where large slabs of lava buckled due to pressure from the molten lava flowing under a hardened crust.

"SQUEEZE-UPS" are bulbous extrusions formed from lava squeezing up through cracks.

"LAVA TUBES" are not known to be present in any of the flows, a few lava channels are present, however.

Low-lying area on the flow are filled with windblown sediments which range from a few inches to more than 3 feet think. Sand-blasting is prevalent over the entire flow, and wind-faceted pebbles of basalt are common.

In order to log this as a find, please send an email to and a photo of one of the above mentioned volcanic features and why you believe it is that feature. If you do not have digital camera capability, please indicate to me by way of description the volcanic feature that is prominently surrounding the public parking area. You may post photos with your log, but please do not post exhibition or descriptive panels with your posts.

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