Snug as a bug in mud

These bugs are slimey, so any mud floating in the water sticks to them. They are also able to cement mud grains together (which is why you wouldn't want these bugs living up your nose). Adding mud grain to mud grain, they build up stromatolites about as high as your knee. That's pretty impressive for a bug so small that when you sneeze it out of your nose it's travelling at about 160 km per hour. It's like humans putting up a building many kilometres tall (and we haven't managed that yet). In lakes and shallow bays in Western Australia, these rocks are slowly growing - cementing mud day by day, century by century. Many are more than 1000 years old. And these little bugs, or ones just like them, have been doing this for a very, very, very long time - 3500 million years in fact.

Now, you might think that it's been a 'long time' since you last put on a clean pair of socks, but we're talking a seriously long time here - a mind-bogglingly huge amount of time that's almost too big to think about. We can talk about dinosaurs first appearing about 230 million years ago and humans just a few hundred thousand years ago, but what does it really mean?

Ofc - 3,500 miUioA (A^ars-a biV borii^^uu^ , la^sAr^evoWi^ d \ ?.. So^a eycAuUo^ Wrp, 0

Here's a way of thinking about it that might help. Hold this book in one hand. Keep reading. Stretch your other hand out to the side. Yes, right out, pointing

your fingers. Now, just imagine that your nose represents when life began on Earth. (I said when it began - not where.) In this book we are going to travel from your nose, across your face, down your arm, as far as the beginning of your fingers. That would represent when dinosaurs first appeared, around 230 million years ago. They became extinct at the beginning of the last joint of your finger. Humans appeared just a few hundred thousand years ago - they are the thinnest piece of fingernail you can snip off.

In this first chapter we are going to travel a long way - from the tip of your nose to your wrist. And, as we shall see, for much of this extremely long period of time (from about 3500 to a little under 600 million years ago), there wasn't much on this Earth, except for bugs, bugs and more bugs - oh, and lots of slime.

Dinosaurs appear

Dinosaurs appear

0 0

Post a comment