NOVA Online: Dating Lava
Photo: Jack Lockwood Excerpted Interview with Jack Lockwood, Geologist with the Hawaiian Volcano Observatory:

NOVA: Tell us about your impressions of the different ecosystems in Hawaii.

LOCKWOOD: We're up here in a very dry, dry area, it's all beautifully clear and you can walk anywhere you want. But much of my work is down in the forest. The Hawaiian word for the rain forest, is Mau Kali. Mau Kali means perpetually muddy. And it is a perpetually muddy place. But that's where the biology is really happening. That's where the plants are most abundant in terms of different kinds of species. That's where they grow fastest, that's the area of prime interest to the biologist. And I think that all geologists, at least myself, certainly thought it was a muddy place, you'd go into it, sometimes you'd get lost. It was a place you'd like to avoid. You couldn't see the rocks very well. But after a couple of years of mucking around in the force, I was again one day mucking around literally. I was walking through a particularly muddy area, and a little bit tired and I tripped, something caught my feet and I fell. quote: If you're trying to determine how the future activity of the volcano will affect the works of man, you've got to know what the volcano did in the past. I was wading through a mud pond. And I fell splat. Just full on my face in the mud. Picked myself up out of the mud. I had a rubber suit on, and actually I was tired. And the mud welled around and what the heck, it felt kind of comfortable. So I stayed there just a little bit to catch my breath. As I was doing this, I started, for the first time I started to hear the birds. I'd never paid attention to the birds in the forest before. And I looked up, and when I looked up in the trees it was a sunny day, but not much sun gets down to the base of the forest. But you could see the forest, you could see the rays of the sun pouring through the trees. And there was a log right above my head, an old decaying log, and that log was covered with liverworts, or all sorts of little fungi and things, and they had little drips of water on them, and I watched them carefully. And they were bursting open. You could see spores back lighted by the sun coming through. And it was beautiful. The little raindrops were creating rainbows. And it was almost a religious experience for me in terms of what happened. I suddenly, dramatically felt like I couldn't breathe. I was so overwhelmed by how beautiful it was. And I had never seen the beauty of the forest before. So I guess after that point, suddenly I realized that a lot of my work up here in the dry part of the mountain, where you can see things, can be integrated with what's going on down in the forest. And this was the beginning of a love affair with the forest. I love the forest. We'd be down there doing work, except it's not nearly so photogenic, it's dark and muddy.

NOVA: Explain why you are collecting charcoal to date lava flows.

LOCKWOOD: What we're doing now, by collecting charcoal is figuring out the ages of these individual lava flows in the flows that buried them. Once we know the ages of the flows that surround these kapukas, we are able to determine how long they have been isolated biologically. But, a very small piece of the action—back to Mauna Loa itself—the overall volcano, first of all, it's the largest volcano on earth. It occupies at the surface here, some five thousand square kilometers. The elevation of the summit is about 13 thousand 600 feet. But there's another over 15 thousand feet of the mountain, of the volcano which lies below the surface of the sea. But looking at this volcano, what we've been able to do in the past 10 or 12 years is to begin to look at the prehistoric history that has never been known before...... If you're trying to determine how the future activity of the volcano will affect the works of man, you've got to know what the volcano did in the past.

NOVA: What impact has your work in dating lava flows had on biological research on the history of the volcano?

lava flow through a forrest LOCKWOOD: ...We've come to realize how frequently the lava flows do come through the forests. And we've come to realize that those forests are continually being destroyed. Individual forests are being isolated by younger lava flows that surround them. So that in effect the volcano has been forcing the forest to change, and it's got to change quickly, you might almost say, because it doesn't, have very long to make change before it'll be buried by another flow. So these processes happen very quickly. That's been the exciting thing of (biological) work. (They've) shown that genetically the plants and animals in these forests modify very, very quickly. Evolution occurs very, very fast in the forest, much faster I suspect than anyone had thought before. And the key to understanding that has been able to understand the absolute chronology.

NOVA: When you look under old lava flows, what are you looking for?

LOCKWOOD: The reason we're going through this exercise in trying to get underneath the younger lava flow is to find that one place where one little bitty bush was growing. If we can find the place where 2000 or 3000 years ago, a bush was growing when that red hot lava came down. The red hot lava would have buried the bush and converted bits of it to charcoal if conditions were right. If we can find bits, even a few, a few tenths of a gram of carbonaceous material, we can send that to a laboratory in Washington, DC., it will be dated by the radiocarbon method. Then we'll know when the plant lived, or rather when it died, and it was of course killed by the lava flow, so that will tell us the age of the lava flow. That's the critical thing we have to learn up here, for the ages of these lava flows, in order to recover the eruptive history of this mountain. How old are the various lava flows that are present at its surface?


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