Spelunking: Crawling through underground caves

Way up in the Far North country, nestled within the northern peninsula of the Keweenaw, itself at the tippy-top of Michigan’s Upper Peninsula, is the old copper mining country. Active in the late 1800’s and early 1900’s, this land provided the metals that would fuel America’s industrial revolution. Early in the 20th century, the mines would all close- not because they’d run out of copper, but because there was simply too much. It was a bitter piece of irony for the region, destroying its economy. There was simply no way to remove the huge thick sheets of copper underground cheaply…

Villarrica is among the most active volcanoes in South America

That’s a surprisingly tricky question; let me start with what is hopefully a helpful analogy. Volcanoes aren’t like old people who might retire from their job or kick the bucket at a predictable age. Volcanoes are much more like a rock band. Most are one-hit wonders, many produce some great hits for a while and then slowly disappear, and others keep rockin’ on for ages.

So how long a volcano remains active for or how long before it’s considered extinct depends on the type. It’s the Rolling Stones vs. Los Del Rio.


There are a lot of factors involved, primarily centered around abundance. Let’s look at the main ones:

Abundance of species

When geologists study the Earth a million years from now, which fossilized species are they more likely to come across: humans or lemurs? Dogs or rhinoceroses? Mice or pangolins?

The fact is, just like the present, not all species in the past were terribly widespread or abundant. We’re unlikely to see many of those more obscure species in the fossil record only because there’s less to be found. …

Reader alert: if you can make it through to the end of this answer, though, I’ll reward you with some cool stuff, I promise!

In the vast majority of cases, the headwaters/origin/source of a river look… boring. Dull and hardly interesting in most cases. Searching out the source of a stream is usually disappointing. Normally I’d show photos, but I don’t have many because these places are so non-impressive that I’d never thought to snap a photo.

As you go upstream, the river continues to divide into more and more tributaries. At first, it’s very clear which is the main…

Delicate materials don’t usually fossilize. In fact, usually nothing at all is preserved because decomposition and predation/scavenging is so ubiquitous. This is true for large animals and plants and especially for delicate materials, but let me give you one of the coolest examples in the world and then briefly explain how the fossils there were preserved.

Florissant Fossil Beds National Monument is in Florissant, Colorado, just a short drive from Colorado Springs. This place is spectacular in terms of fossils. …

Credit: Francesco Ciccolella

That’s a tough question because scientists like to know everything and we wish everyone felt the same as us, but I think the honest answer to this is: how uncertain we are about our results. The reason for this is probably not what you’re thinking, though.

A lot of people who distrust science are going to answer “Aha, I knew it! Showboating huckster scientists, you can’t trust them! They pretend to have all the answers and they know nothing!”

Well, that’s not true either. But let’s talk about uncertainty in the sciences for a moment.

Uncertainty is a fact of…

Petrified Forest National Park, credit: https://utahsadventurefamily.com/petrified-forest-national-park/

It’s a common argument made by creationists refuting radioisotope dating. There are dozens, perhaps hundreds, of examples of fossils that are millions of years old, even a hundred million years old, that radiocarbon dating shows are only a few thousand years old? How does a geologist explain that?

Our answer: because you can’t radiocarbon date fossils. If I had a nickel for every time I saw a question based on a fundamental misunderstanding of radiometric dating, I’d have… a whole goddamned lot of nickels.

Here’s the short version of the answer: carbon dating measures the ratio of radiogenic carbon, C-14…

Without a doubt, the title holder for “World’s Toughest Rock” (not a mineral, but a rock) has to go to Banded Iron Formation, or at least to a related variety of ironstone (there are several).

Anyone who’s ever dealt with Banded Iron Formation, which we usually refer to as BIF, knows that it’s a beautiful rock that is also an absolutely gnarly bitch to break or cut. The reason is pretty simple: it is composed of alternating layers (bands) of quartz, which is already a pretty hard material, and hematite. Hematite is Fe2O3. It is hard. It is iron. …


As a geologist, I’m often asked about the arguments that creationists- namely young-earth creationists- use to advance their views and discredit modern science. Many people dismiss creationist arguments as idiotic nonsense, but I disagree entirely with that. Their arguments are clever and designed to confirm the beliefs of those who are already creationists.

Yes, they are terrible and wrong, but the way the best creationist arguments are cherry-picked and cloaked in a veneer of science is something special and, in many ways, quite unique to the anti-science community. …

A view of the volcanic site on the Reykjanes Peninsula following Friday’s eruption in Iceland, March 21. REUTERS/Cat Gundry-Beck

I am a volcanologist with expertise in magmatic plumbing and here is a very common question with answers based on my audience:

What causes a volcano to erupt?

To the very young child: Lava makes a volcano erupt. It’s rising up out of the ground and it needs to come out somewhere. Bam, volcano! Are you still with me? Oh… no, you’re already on the jungle gym? Ok.

To the elementary school student: I used to give volcano talks to elementary schools so this is an easy one. You need to have magma, but you also need to have gases…

Craig McClarren

Geologist, a lover of all science, father of a young child, published writer on Forbes and Mental Floss

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