Kilbourne Hole — Southern New Mexico’s largest sunken crater

The Kilbourne Volcano near Deming

Photo by Thomas McGuire

The Kilbourne Volcano near Deming

Try to imagine, if you will, traveling along a deserted, sandy, narrow, semi-graded track in the middle of the south central New Mexican desert. Everywhere you gaze, there is a myriad of thorny mesquite, interspersed with the ever present chaparral brush (also called creosote bush or greasewood), dry yellow grass, and tall yucca plants.

Here and there a fast moving lizard darts across the sandy road in front of you, or maybe even a slithering prairie or diamondback rattler crosses your path.

Eight or so miles along this desolate stretch you see hills rising out of the flat desert floor. These hills stretch for almost two miles north to south and rise to a height of nearly three stories. They are also covered with chaparral and yuccas, but there is one large difference between these and any others in the area: These hills are actually sand dunes that form the east and north rims of an ancient volcanic steam crater known as Kilbourne Hole.

The sandy track takes you to the south rim, and instead of being up on a lofty mountain dome, you find yourself still on the desert floor peering into a gigantic hole, because Kilbourne is actually a sunken crater.

The crater is actually called a marre, and scientists, who know far more than I, theorize that lava flowing from nearby Aden Crater flowed over the earth’s surface and cooked the west limestone beneath. After a time, there was a steam explosion that produced the Kilbourne Hole. From the south the view is spectacular. The “hole” stretches for more than 1 1/4 miles across and reaches a depth of nearly 300 feet in places.

Peridotite or Precious Green Olivine at Kilborne Volcano

Photo by Larry Lightner

Peridotite or Precious Green Olivine at Kilborne Volcano

Not only is Kilbourne unique in being Southern New Mexico’s largest steam crater, but it has another distinction: It is the site of a rare, semi-precious gemstone known as Peridotite or Precious Green Olivine.

This gem lies mostly on the inner eastern and northern slopes just above the rimrock, and is found in various sizes of crumbly rock up to the size of one’s fist, or it can be found commonly in “bombs” which are softball sized chunks of rock which when broken open, reveal the semi-precious olivine.

Besides the green olivine, we found rusty reds, golds, purples, brown and black forms of the gem. My wife descended to the floor of the crater and there found some interesting “fingers” which resembled polished jasper or marble.

If you go in search of this stone, be prepared. You’ll need a rock hammer, a small bucket, a five gallon bucket left at your vehicle, safety glasses and leather gloves. The weather is mostly sunny and very bright, so take sunglasses, a brimmed hat, long sleeved shirt, long trousers, and either sneakers or hiking shoes.

The hike up and over the dunes can be very physically demanding because the east slopes are comprised of soft, deep sand, and the west slopes are very steep and rocky - and you must descend 100 to 200 feet to get the the “good stuff.”

And . . . you must always be on the alert for desert rattlesnakes!

I’ve been to Kilbourne twice and each time I came away with a five gallon bucket of peridotite for my rock garden. Outside of Kilbourne, you can only find this gemstone in Southwest Arizona, St. John’s Isle in the Red Sea, and in Burma.

The best and only way I know to get to Kilbourne is to travel Interstate 10 between Deming and Las Cruces, New Mexico to Exit 116. Go south off the interchange and take an immediate left onto a paved road which parallels the interstate to the east. A couple of miles on, the pavement ends and you turn right and head south for several more miles until you reach railroad tracks. Here the graded road turns left and you follow it and the tracks both east then south. From the time you leave this last pavement it will be 28.5 to 29.5 miles (depending on the accuracy of your odometer) until you reach a tiny, deserted junction with a shed or two. Turn right and head west for almost nine miles to the south rim of the volcano.

All of the dirt roads are graded but rough with washboard and some soft, drifted sandy areas. I recommend a four wheel drive vehicle or at the least, a two wheel drive pickup. This is no place for a passenger car, even if it is front wheel drive! Allow two hours driving time once you leave the pavement.

If you’re a rockhound or just like to see spectacular sights, then Kilbourne just may be your ticket.