The First Plants:
600 Million Years Ago
They had not walked far, climbing over the broken rocks, when it began to rain. Heavy round drops of water splashed down on the children, and within a few minutes they were soaked. It rained so hard they could not see, but they bravely struggled on, holding onto each other's hand.
It seemed to rain for a long time, and Alice tried shouting at Zack that they should stop walking. But she couldn't know if he heard her over the roar of the water splashing down out of the sky.
She wondered if all that water would put out the volcanoes they'd seen, and she imagined she could hear hissing noises around them as the fires turned the rain to steam.
A strong wind started to blow and for a moment Alice lost her balance. She clung to Zack, who leaned into the wind and stomped sturdily forward. He was shorter than she was, but he weighed about the same and had less trouble staying on his feet, than his tall, slender sister.
As suddenly as it had begun, the rain stopped. The darkness cleared away.
"Look!" Zack pointed at the sky.
Now, this looked more like home. The sun was still a bit brighter than it should be, but it wasn't moving so fast anymore. The sky was its proper shade of blue, and there were little white clouds drifting lazily across its broad expanse.
"There's an atmosphere now!" said Alice happily.
"What's an amos-fear?" asked Zack.
"That's the sky," she explained. "The whole earth is wrapped in a blanket of air, and the reason the sky looks blue is because the light from the sun gets bent when it comes through our atmosphere and it makes a blue colour. At the beginning of the world there was no air, and that's why the sky looked all black."
"Do we need air?" asked Zack.
"Yes . . . " Alice was puzzled. She knew you did need air. To breathe - to live! So she did not understand how they could have stood on the earth at the beginning of time, before there was any air to breathe.
"Well, maybe you and I don't need air," suggested Zack, helpfully.
"No silly, everybody needs to breathe!"
"I don't," said Zack, having made up his mind on this point.
"Yes you do!" Alice was not the sort of person who gave up an argument easily, especially when she knew she was right.
"No, I DON'T"
"YES, YOU DO!"
They had a fight then, which really doesn't require description. There was some pushing and someone's finger got stepped on, and someone else's feelings got hurt. But in the end they made up, and said they were sorry, and Zack gave Alice a hug, which she returned with as much grace as might be expected, given that Zack never did admit she was right.
When they climbed over the next pile of black rocks (which were not quite as black or as sharp as the ones they'd seen earlier) they saw that the land dipped down into a flat sheet of water which spread all the way to the horizon, where it disappeared into a sky so blue you couldn't tell where the water ended and the sky began.
"It's an OCEAN!" exclaimed Alice with delight. She had always wanted to see the ocean. Dolphins were her most favourite animals and she harboured a not-very-secret dream to swim with them someday.
"There's no sand," objected Zack, whose personal vision of an ocean included lots of sand, trees with long trunks and clusters of spiky leaves at the very top, and brown men with whistles sitting on very tall wooden chairs.
"I'm going to go swimming!" said Alice enthusiastically, and she scrambled down over the smooth tumbled stones to the edge of the water. Zack followed her.
"Eww!"
The water wasn't clean. There was green slimy stuff floating on top, all around the edge of the rocks, and for several feet out.
"That's yucky!" said Zack, decisively. Then he added, "I don't want to swim in THAT."
"Me neither!" agreed Alice. She knelt down next to the water and poked at the green stuff with her finger, "But Zack, do you know what this stuff is?"
"It's yucky."
"Besides that, I mean!" She didn't wait for him to answer, "These are the first plants. They're the first life on earth! They are green because they're using the sun to make their food - that green stuff is called chlorophyll. And when they make their food, they give off oxygen, which is what WE breathe. Zack, do you know what that means? The plants are the ones that made the world so that people like us can live and breathe. Oxygen is left over when plants make food. Oxygen is . . . is . . . like plant poo!"
Zack giggled, "We breathe poo?"
Alice laughed, "And you know what? When we're finished using the air, then we breathe out carbon dioxide and that's what plants like to breathe! So they give us oxygen and we give them carbon dioxide, and these little plants here are making the first oxygen in the world! Isn't that neat?"
Zack wasn't listening. He was laughing too hard. "We breathe PLANT POO!"
Alice looked around at the bare rocky landscape. It was absolutely silent except for Zack's snorts and giggles and the gentle lapping of the water on the shore. She noticed there was no salt smell in the air, and wondered when did the sea become salt. But without her books or the computer, there was no way to find the answer to that question. They were all alone, and Alice was suddenly aware that they were indeed walking home from the beginning of the world.
"What a long trip this is going to be," she thought to herself, and for a moment she felt very lost and alone. Then another thought occurred to her, "Wow! I got to see the first plants!"