By Joe Darby
If you took a trip across the Atlantic Ocean the year I was born, 1941, and took the same trip today, you’d have to travel about almost seven feet farther before you touched land.
What kind of nonsense is Joe getting up to now, you may well ask. Well, the above statement is absolutely true. The Atlantic Ocean, you see, is spreading wider every year, at a rate of about one inch annually. It’s been doing this for about 170 million years. And it’s all due to the phenomenon known as plate tectonics. You may have heard of this geological wonder, which was only proven and accepted by science around the 1960s.
The earth consists of a series of gigantic plates, like a big round jigsaw puzzle, which ever so slowly move, bump into each other, rub each other and otherwise change the look of our planet over millions of years.
Yes, folks this week’s column is, as you may have guessed by now, pretty much of a geology lesson, a subject that I have become fascinated with in the last year or two. I’ve always been an avid reader and I would suppose that more than 90 percent of my books have been about history, in almost all of its forms.
But I saw a couple of TV shows about the amazing geology of the earth and I’ve been reading about what makes our earth tick ever since. I’d like to share some of my findings with you, because I think they’re just so doggoned interesting. It this topic leaves you cold, that’s fine and I hope next week’s offering will be more to your liking.
So, for those of you nice folks who have stuck with me, let’s talk about the history of this wonderful old world of ours. (But first, for those who insist the world was created in seven days, as the Bible says, you will be put off by what I have to say. However, most churches these days accept Genesis as an allegory and believe that God caused the miraculous processes that led to the formation and development of earth.)
I’m not going to go into great detail, both because of space considerations and because some of the story would get pretty tedious. But, long story short and in an oversimplification, the earth was formed, along with the rest of the solar system, about 4.6 billion years ago. It consists of a core, the planet’s center which has temperatures and pressures of incredible heat and power. Above that is the mantle, on top of that is the lithosphere then the crust. Which is where we live. Most geologists believe that giant areas of heat convection in the mantle, like water moving about in a pot of boiling water, cause the various plates on the crust to move about.
Over the more than 4 billion years of the existence of our planet, its appearance has undergone drastic changes. For hundreds of millions of years after it formed, it was a glowing, red hot mass. Then, as the planet began to cool, the plates formed and have been changing the appearance of earth ever since. There are two types of plates, continental crusts and oceanic crusts.
About 540 million years ago, almost all of the continental crust plates clumped together into one gigantic land mass, stretching from pole to pole. It later broke up and the plates have been moving about ever since.
About 170 million years ago, the Atlantic Ocean began to open up, as materials from deep within the earth began rising and spreading out, at what’s known as the mid-Atlantic ridge. Like a gigantic conveyor belt, they have been widening the ocean until it has reached its present size. In another couple of hundred million years, we will be a lot closer to Asia than we are to Europe.
Earthquakes, volcanoes and the pushing up of mountains occur where these plates come together and push against each other. The process is slow incredibly slow, we can not see the changes. But if you look at a map and notice the shape of South American and that of Africa, you can see where the two once perfectly fitted together, again like that jigsaw puzzle.
There’s lots more we could talk about here, but I’ve probably written enough. If you are interested, and it would be nice if you are, search for plate tectonics on the Internet. There’s lots of good sites that can go into more detail than I can here. And you’ll see, like my headline says, the earth ain’t what it used to be!