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Here’s a way to put geologic time scales in perspective.
Lay out the 4.6 billion years since the Earth was formed on a football field and we can see where the milestones would appear:
Start at the goal line and go from left to right down the field.
The first milestone is the appearance of rocks at the 14-yard-line (3.96 billion years ago).
At bit further on, at the 22, the earliest organic structures show up. Then, just two yards away, on the 24-yard-line, there’s the earliest evidence of life in the fossil record (3.5 billion years ago).
Time and the Earth march on, gaining ground without providing evidence of anything flashy, or much of anything at all.
We move past the 30, the 40 and across midfield. Then we go way down to the 12-yard-line, 88 yards away from the starting point
That’s when the earliest shelled animals appear, about 570 million years ago.
Now things happen quickly we drive down toward the goal. It’s kind of a hurry-up offense, speaking in geologic terms, of course.
Fish appear at the 11-yard-line (510 million years ago), land plants take root on the nine-yard-line (430 million years ago), amphibians show up on the eight-yard-line (375 million years ago) and reptiles come out at the seven-yard-line (330 million years ago).
We’re getting close to goal line, so let’s bring in the dinosaurs. Ah, there they are at the five (245 million years ago). Here come mammals at the four (200 million years ago) followed by birds at the three (160 million years ago).
Hold on, fans! The dinosaurs are coming out of the game. They go extinct on the one-yard-line (65 million years ago).
We’re down to the one-yard-line and still no humans? Nope. Check the spot a half-yard out. Not there, either.
We have to get down to just 1.5 inches from the goal line (2 million years ago) before the first humans get into this game. Another 178 million years or so and we’ll have been around as long as the dinosaurs were.
— Thanks to Angela Obolsky, a member of Sharon Mosher’s staff, for putting this information together.
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