Craters of the Moon National Monument and Preserve … and Other Stuff


Post by Jim

We were on another planet!

Well, it seemed like we were on another planet. Craters of the Moon National Monument and Preserve is appropriately named, that’s for sure! The park consists of unusual terrain that features a very nice campground, volcanic cinder cones, lava tubes, 500+ caves, great ranger led hikes, examples of lava types and on-going science research. That’s me popping up out of a lava tube.

After our visits to Yellowstone and Grand Teton National Parks, we thought Craters of the Moon might be a let down, but it wasn’t!

We stayed at a campground in Arco, Idaho, not far from Craters of the Moon. Here’s a little Arco trivia: Arco became the world’s first nuclear-powered city in 1955. The reason that the government chose this place as one of its nuclear test-sites is kind of obvious if you think about it. It’s far away from everything and not too many people live here. If a nuclear accident did happen, probably no one would notice. Like the time the only fatal USA nuclear accident occurred. Guess where? In Arco, Idaho. Three servicemen were killed In 1961 when there was a core meltdown in the National Reactor Testing Station. You probably never heard about it.

Here are two pictures of the main street in Arco.

The one on the left was taken at noon on Monday, September 4, 2017 (Labor Day Holiday) and the one on the right was taken on the other side of the street at 5pm the same day. Notice any difference? The one on the left shows a car driving down the street in the distance. I’m not saying there ‘s nothing going on in Arco, but…

Seriously though, Arco is a cute, and a bit odd, little town, with friendly people. It’s a good basecamp location when exploring this part of Idaho. There are a few things worth mentioning about Arco, and the surrounding area, that I’ll touch on near the end of this blog entry.

20170904_121028This is what Craters of the Moon looks like from the road driving to the entrance. The landscape changes from farmland to a 750,000-acre otherworld covered in lava.

Our first stop in Craters of the Moon was the visitor center. The displays gave us a great deal of information about park features, park history, folks who explored the park and Native Americans that lived within the park boundaries. Here are a couple of interesting facts:

Craters of the Moon became a National Monument in 1924 after an explorer/photographer named Robert Limbert described his experiences at Craters of the Moon in a series of photo essays published in newspapers and magazines. The most well known was a 1924 National Geographic article entitled “Among the ‘Craters of the Moon’.”  Around 200,000 people visit this National Monument every year.

In 1969, Apollo 14 astronauts Alan Shepard, Edgar Mitchell, Joe Engle, and Eugene Cernan were taken by NASA to Craters of the Moon so they could learn the basics of volcanic geology in preparation for trips to the moon. They were pilots, not geologists. A lot of the moon’s surface is covered by volcanic materials, like lava, so it was important that they know something about lava. They also visited volcanic sites in Hawaii and Iceland. NASA reasoned that visiting these places would help the astronauts become educated observers who could describe Moon surface features to geologists back on Earth. Years later, the living Apollo 14 astronauts commented about how visiting these places prepared them so well for their missions to the moon. The Apollo missions were not the end of space science research at Craters of the Moon. Here is a short YouTube video that explains on-going research: Craters of the Moon Scientific Research

20170903_113938It’s really easy to get to the main Monument attractions, just drive along the one-way loop road that begins and ends near the Visitor Center. The road will take you past parking spots and turnouts near features and hiking trails.

One of the hikes we took was to the top of a cinder cone named Inferno Cone. Don’t let the picture fool you. What looks like the top is not the top. Just over the top you see in the picture … is more cinder cone to climb. Eventually we did get to the top.

20170903_114739This is the material that makes up the cinder cone. It looks almost glass-like with real sharp edges. It wouldn’t be good to walk on with bare feet although we did see folks wearing rubber flip-flops. I’m betting some of them were very sorry for their choice in footwear about halfway up.

The view from the top is amazing. On one side there are cinder and spatter cones lined up along the Great Rift. Idaho’s Great Rift is a 52-mile line of low volcanoes and spatter cones that formed on a fissure. None of them are active today. It’s believed that the magma hotspot under Yellowstone National Park was once under this part of Idaho. As continental plates shifted, the magma hotspot ended up under Yellowstone. On the other sides of the cinder cone are views Craters of the Moon lava fields and, in the distance, Idaho farmland. As you can see, some trees have grown on top of the cinder cone.

After our trek up the cinder cone, we stopped and hiked on several trails as we drove around the loop road. Some things we saw were lava monoliths, volcanic craters, spatter cones, island-like lava fragments and caves. In some places where the lava is deteriorating, plants and trees are taking over and almost seem abundant.

It’s worth a little time to talk about the lava tubes and caves. One of the spur roads off of the main loop road takes you to the cave area hiking trail. The main caves on the trail are Dewdrop Cave, Beauty Cave, Boy Scout Cave and a lava tube, Indian Tunnel. We did a ranger led hike to Indian Tunnel. According to the ranger, there are over 500 caves and lava tubes in Craters of the Moon that can be explored.

You need a permit to enter any of the lava tubes or caves (we got one) and as part of the permit process you are asked if anything in your possession (shoes, camera, hat, etc.) has been in a cave since 2005. If anything you have with you has been in a cave you must not take that item into any of the caves or lava tubes in Craters of the Moon. There is a disease, white-nose syndrome, that is killing bats in North America and it spreads from items that have been exposed to it in caves. The ranger leading our hike was assigned here because his field of study is bats. He was quite serious about it and explained that some of the bat species in Craters of the Moon are going to go extinct because of the disease.

Here is a slideshow, probably too many slides, of some caves and lava tubes we explored at Craters of the Moon:

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During our hike to Indian Tunnel lava tube, the ranger pointed out all kinds of plants we wouldn’t have noticed, talked about the different types of lava, explained how lava tubes are formed, talked about caves, bats and many other things I probably don’t remember. I highly recommend the ranger led hikes at Craters of the Moon if you want to get the most out of your visit.

IMG_8738One interesting hole in the ground we passed had ice in the bottom of it. Even though it gets blazing hot at Craters of the Moon, some holes/caves stay cool enough that winter ice does not completely melt during the summer. Native Americans used these places like refrigerators to keep things from spoiling.

Indian Tunnel lava tube is big. Lava tubes form when a lava flow hardens on the outside while lava still flows within it. After the flowing lava is gone, a hollow, hard tube remains. We walked down a flight of steps to get into it. It was a warm day but there was a noticeable temperature drop in the lava tube. For the adventurous, there is an 800 foot scramble over rocks, not very difficult, to get to a hole you can crawl out of at one end. The blog cover photo is me crawling out the hole.

Hiking around this place, one can’t help but notice that there seems to be two distinct types of lava, crumbly and smooth/ropy. The crumbly, chunky type is called áa (pronounced “ah-ah” like in ah-ah it hurts my feet!). It forms from thick, viscous lava. The smooth/ropy type is called pahoehoe (pronounced ‘paw-hoey-hoey”). It is formed by very liquid, fluid flowing lava. Both names came from Hawaii.

áa lava (crumbly) on the left and pahoehoe lava (smooth/ropy) on the right (Phil, Alexandra and Carol)

Craters of the Moon is a great place to visit if you want to see something different. It’s a volcanic park unlike any other we’ve gone to.

As I said earlier, we stayed in Arco, Idaho as a base for our trip to Craters of the Moon and exploring the surrounding area. One day, we decided to eat out and picked a local place called “Pickle’s Place – Home of the Atomic Burger”. The place was busy and the food was good. Across the street was a town park and sitting in the middle of the park was a submarine sail. Of course we had to check it out.


The sail came from the USS Hawkbill (SSN-666). Turns out the nuclear reactor that powered it was developed at facilities near Arco. To show the Navy’s appreciation for the effort, they donated the sail after the ship was decommissioned and scrapped in 2000. 20170903_152114

The added bonus to this little park was the little Mega-Peace Museum that was housed inside of a metal shipping container right next to the submarine sail. The focus of the museum is the history of the secret and commercial atomic energy work done at the Idaho National Laboratory Atomic Facility nearby. The volunteer in this little museum is a retired physicist that worked in the atomic laboratories. He was full of fascinating information and gave a great description of the old pictures, mementoes and documents being displayed. He did creep me out a little by talking about how good it was that countries had nuclear weapons that deterred each from attacking the other. He also went on about how many fewer wars and war causalities the world has suffered since nuclear weapons have been deployed. He was much too happy about it in my opinion. Nonetheless, it was well worth the couple of hours we spent there. On the back wall of the museum was a display talking about the USS Hawkbill.

One interesting and a little odd tradition that’s ongoing in Arco is featured on the hillside behind the park. It’s called the “Hill of Numbers”. For many decades, the graduating classes of the local high school have been decorating the nearest mountain with the last two digits of their graduation year.


The last side trip we took while in Arco, was a tour of the EBR-1 (Experimental Breeder Reactor 1) Atomic Museum, which was designated a National Historic Landmark in 1965. This reactor was the first one in the world to generate electricity using atomic energy on Dec. 20, 1951.  It produced sufficient electricity to illuminate four 200-watt light bulbs. The next day, the reactor produced enough power to light the whole building. The real purpose of EBR-I was not to produce electricity but to prove a breeder reactor was possible. A breeder reactor is a nuclear reactor that generates more fuel than it uses. Experiments done at EBR-1 showed the reactor was producing fuel, proving the theory. Besides generating the world’s first electricity from atomic energy, EBR-I was also the world’s first breeder reactor. Interest in breeder type reactors declined after the 60’s when more uranium was found and cheaper ways to create nuclear fuel for reactors were developed.

20170904_155637_006Our tour of the reactor building began with a lecture that explained, in technical detail, how a breeder reactor creates fuel. We also learned that EBR-1 was used for experimental purposes in order to develop more advanced reactors. During one experiment, November 29, 1955, EBR-I suffered a partial meltdown during a coolant flow test. The flow test was trying to determine the cause of unexpected reactor responses to changes in coolant flow. After the lecture, we took a self-guided tour of the reactor building going room to room. I had a real problem restraining myself in the control room.

Believe it or not, these things were supposed to be part of a nuclear powered airplane. The United States Army Air Force started a project to build a nuclear powered airplane in 1947. In 1951 the project was transferred to the Atomic Energy Commission and it was terminated in 1961. These huge contraptions are nuclear reactors that were designed to heat air to drive jet engine turbines. That’s my wife standing in the middle between them. Of course it didn’t happen. One of the museum employees said it was a big waste of money and that most everyone knew the plane would never be developed. Can you imagine the size of the airplane these things would be in?20170904_140211

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20170904_160515Next to the reactors was a huge lead-shielded train engine on four tracks. This thing was supposed to pull the reactors to a huge hanger where the plane was to be built. It did pull one of them down the tracks where the reactor successfully started and powered 2 jet engines in 1955.

If you are in the Arco area, the EBR-1 Atomic Museum is a must see. It’s open Memorial Day weekend through Labor Day weekend — seven days a week — from 9 a.m. to 5 p.m. Admission is free.

This blog entry wraps up our trip through Idaho. It’s a beautiful state with lots to explore. We only touched on a few of the many things to see and do here so we’ll be back for sure!

Next stop, Bryce Canyon, Utah!

Real Estate Bargain in Arco, Idaho

One thought on “Craters of the Moon National Monument and Preserve … and Other Stuff”

  1. What’s that creature coming out of the crater?!?!?! Hot Lava Man?!?
    Great Pics! Very happy you’re enjoying retirement! Keep on Airstreamin’ !


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