Thursday, 18 July 2013

Craters of the Moon Idaho

This National Monument is called the name it is because scientists used to imagine that the surface of the moon would be very like the surface of the park. Having been to the moon, they now realise that the park is more like the surface of Mars than the Moon, never-the-less, there are no plans to change the name.

It is a most unusual place and is the result of volcanic activity as recently as 2000 years ago. However, it is unlike two of the three volcanic areas we have visited in the past few years (Iceland and Vesuvius) and only has underground similarities with one - the Undara Lava Tubes in Australia.

Long View

Our first view of CotM was from an overlook on the road leading to the park and in front of us was a large dark grey field of lava stretching off in all directions into the distance which was described as “a large field of vomit” by an early settler passing through the area along the Oregon Trail.

Closer up it still looks strange but the shapes of the mounds

Craters Second Viewand the types of cinder / lava enable geologists to work out the history of this enormous lava field.

Inferno Cone

There are volcanic cones which you can walk up such as this one named “Inferno”


Lava flows which you can walk through

Cinder Cone

and cinder cones which you can climb up and go inside of – these were the source of much of the lava flows in the area.

Bomb-1 Bomb

As the volcanoes erupted, they threw out large solid chunks of lava known as lava bombs. These are very heavy and vary in size from large football sized pieces to car sized pieces.

Lava flow showing Titanium Magnetite

A peculiar characteristic of some of the lava is its blue tinge which comes from Titanium Magnetite on its surface (and the red is ion oxide which is slowly rusting)

Lava Field-1

The most recent volcanic eruptions here were 2000 years ago and hence we are walking within a relatively recent geological event.

Lava FieldThis lava field and the numerous volcanic hills left behind results from a rift in the earths plate letting out magma. The earth’s surface has been moving over a stationary “hot spot” for thousands of years and currently the “hot spot” is beneath Yellowstone – this is thought to be the most probable spot for an eruption if it were to happen in the near future.

Two Lava Flows

And here we have evidence of two lava flows – that at the top of the photograph was colder than that at the bottom (which looks smoother because it was hotter and more liquid when it flowed).

Folding Lava-1 Folding LavaThis lava has frozen into folds – described as a bit like flowing honey which also can move in a fold like manner.

Wherever you get flowing lava, you get lava tubes

Cave Entrance

which you can get into much like climbing down into the tube (which is much like a cave) . A lava tube is created when flowing lava cools on the outside creating solid tube walls thus enabling the lava inside the tube to remain hot and still flow, often for many miles.

Indian Tunnels is one such tube

Indian Tunnel

and is about 50 ft high and wide. Entry is through a hole in the collapsed roof.

Indian Tunnel-1

The tunnel floor quite clearly shows remnants of the (now) solidified lava flow.

Cave floor

The volume of lava which would have flowed through this tunnel is very large.

The tunnel is called Indian Tunnel because near to it are a

Indian Tunnel Rings

number of stone rings on the ground which are thought to have been constructed by Shoshone and Bannock Indians in the distant past.

Eventually the tunnels collapse (usually parts of the roof).

Collapsed Tube-1

In some cases, the collapse occurred very soon after the lava stopped flowing (as above) resulting in a soft collapse where the roof of the tunnel simply sags inwards.

Collapsed Tube

A hard collapse happens when the roof is cold and it shatters as it collapses.

Pat entering cave

Buffalo Cave required more of a scramble to get in because the tube was not very large.

Pat entering cave-1 Pat in cave

Once inside, it was about tall enough to stand in


and if you turned your torch out, then you could just make out daylight at the other end of the tunnel.

In summer the Craters is one of the driest and hottest places imaginable, the day we were here the air temperature was 97F and the ground temperature was said to be approaching 140F in places because it was black and thus absorbed the heat. In winter it is covered with thick snow and this means that plants and animals can adapt and survive

Field of Buckwheat

such as this field of Buckwheat which copes with the dry summers by having a long tap root and long side roots which spread out into the gaps between one plant and the next in order to extract as much moisture as possible. If they grow too close together there is not enough moisture and they die.



Much to our surprise there were ferns growing in the shade of the lava rocks and extracting water from deep down in the soil.

We also saw

Blazing Star

Blazing Star which closes up as soon as the sun gets hot and reopens in the cool of the early evening


and Monkey Flower which was past its best when we were there, it is a bright pink in early June. Monkey Flower was used by Native Indians as a medical treatment for infected wounds due to its high salt content – they turned it into a poultice and put it on wounds.

Friendly grasshoppers

and two brightly coloured amorous crickets who survive not only the shortage of water but also the hot rocks.

The Rangers who took us on a number of guided walks and cave explorations were as enthusiastic as ever about their park and were determined that we would leave more educated than when we arrived. We can assure them that we did.

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