Posts Tagged ‘volcano formation’

The Riddle of Red and Black

September 22, 2019

Guy Noir, the Prairie Home detective, spent many years trying to puzzle out answers to “life’s persistent questions.”

Some of those life questions are very important, such as how will I make a living?; what career should I  choose; is there life after death? 

Others are not so important as that, but nevertheless persistent, which is to say. . . they keep coming back again.

This morning I find myself researching, in order to answer a question that has perplexed me for a long time, ever since Pat and I started visiting the Hawaiian Islands about a dozen years ago.

The question is: What’s up with these red rocks and black rocks that seem to constitute the entirety of this Hawaiian island archipelago?

Spoiler alert: I haven’t completely figured it out yet. I will be describing herein my path of wonder, not necessarily giving you an informed report on the subject of red rocks/black rocks in Hawaii.

While I have not yet fully discovered why some Hawaiian rocks are red and others are black, I have managed to gather some learning along the way.

In many ways, I am person who is driven by an appreciation for lifelong learning.

The ancient dynamics and pyrotechnics through which these islands were formed is described in noteworthy detail here:

    https://en.wikipedia.org/wiki/Evolution_of_Hawaiian_volcanoes

You can learn far more about this subject by following the above link. 

But getting back to my little take on it . . . In our ten visits to Hawaii, the photo that I snapped which best shows what lava looks like is:

Formless

This dark gray/black solidified lava flow is called pāhoehoe. You see it throughout all the islands, but mostly on the big island, Hawaii, because it is the newest island, and the one that still displays an observable continuance of recent and still-active volcano activity. It’s fascinating stuff, especially for a curious person like me who took a geology course a long time ago.

We enjoy traveling these islands, year after year. In noticing the vast array of different volcanic rock formations, this question about the red rocks keeps popping up, as “one of life’s persistent questions.’ This never fails to fascinate me. 

Here’s a pic, taken a few years ago on Maui, that shows two layers of black rock with a layer of red rock between them.

RockStory

So we can see that there is some kind of “story” told in these rocks, some sort of history.

Geologic history, Earth history. Hawaiian Islands are perhaps the best location on the planet to identify features by which Earth reveals itself, by telling, in the rock, its own story.

SO, what about that strip of red rock in the middle? you may ask? I’m glad you asked.

I don’t know, but I did ask a Hawaiian about it.

As she began driving our tour bus up into Waimea canyon, I asked Jana about the red rocks, and she said the difference was:

“Rust.” The red rocks have rusted. And, she said, they are older.

I greatly appreciated her immediate answer. It has helped me a lot. It does seem, however, a little too simple for my over-active mind to accept completely. Nevertheless, her concise explanation was confirmed a few days later when I found online a Galapagos report from Cornell U:

     http://www.geo.cornell.edu/geology/GalapagosWWW/LavaTypes.html

Herein I found an authoritative source confirming that the difference in color, in some cases, is “a reflection of age. The older ʻaʻā . . . has weathered and the iron in it has oxided somewhat, giving it a reddish appearance.”

And that’s good enough for me to understand a little bit about what is going on in these vast, ancient islands, which represents processes that have built up our vast, ancient earth.

Meanwhile, back at the beach, I found, two evenings ago, a different working out of the red/black interface.

KaRoksRedBlk

In this scenario, I surmise that, somewhere along the ancient timeline, red rocks were weathered down to red sand and grit, then deposited at low places. During that time, the volcano or the weather must have torn black boulders loose. The black rocks tumbled down into red sands as what you see here. It appears to be black lava rocks trapped in red sandstone, nowadays being gradually dissembled by the thrashing Pacific Ocean.

Or something like that. That’s my answer for the riddle of red and black, one of life’s persistent questions.

  Glass Chimera