The World's Foundations; or, Geology for Beginners · Ch. XI · Unit 2: Part II: Ancient seas and coal forests
12. Earliest ages
Goal: Your child can describe the book's picture of the very early earth and explain why the author calls it a possible explanation, not a certainty.
You'll need
- The book, open to this chapter
- A grape and a raisin (or a fresh and a dried apple slice)
- Paper and colored pencils
What's in the book
Chapter XI says geology cannot tell us about the first creation of the world, then describes one idea borrowed from astronomy: a ball of fiery gas cooling to a liquid, then to a solid crust that wrinkled, with a boiling ocean forming from the steam. It gives the opposite view too, and ends with a word-picture of the bare early earth.
The lesson, step by step
A question to start
SayImagine the earth before there were any trees, animals, rivers or mountains. What do you think it looked like?
Listen, then read.
Read the chapter together
Read Chapter XI (pages 101 to 106). The author is careful from the first line:
GEOLOGY can tell us nothing about the first creation of the world.
The three stages
In plain words, the idea she describes: first a ball of fiery gas; then, as it cooled, a glowing liquid ball; then a hard crust on the outside. As the inside kept cooling and shrinking, the crust wrinkled.
The crust would, therefore, rise and sink in vast ridges and hollows, somewhat like the wrinkling skin of a drying orange.
Compare the grape and the raisin: as the inside dried and shrank, the skin wrinkled.
The first ocean
Steam in the hot air above cooled and fell as rain, until the whole earth was covered by a hot ocean. The water gathered in the low places, low lands rose, and the first simple plants and animals appeared.
Two sides
Giberne gives another view too: some people thought the earth was always solid and cool, and that geologists should stick to the crust. Her conclusion:
We can but hear opposite ideas, and wait for fuller knowledge.
Draw the early earth
Read her word-picture aloud slowly, beginning:
Can you picture to yourself our beautiful earth in those early days ? A wide waste of ocean, over which no ship was ever seen to sail ;
Your child draws it from her description: dim light, low bare rocks, wide ocean, perhaps a little seaweed, no animals to be seen.
Tell it back
Ask your child to tell the story of the early earth in the order the book gives it, then say which part the author says we cannot know for certain.
What we know now
Scientists now think the earth formed about 4.5 billion years ago from dust and rock circling the young Sun, and that it was at first extremely hot and largely molten, so Giberne's first idea is close in spirit. As it cooled, a crust and oceans formed. The oldest known mineral grains are about 4.4 billion years old, and the oldest signs of life, from tiny one-celled living things, are about 3.5 billion years old. Mountains, though, are not wrinkles from shrinking; they are pushed up by the earth's moving plates.
Afterwards
Notice it this week: look at a full moon with binoculars, or at a photo of the Moon. Its bare, cratered face gives an idea of a world with no air, water or life.
Answers to the book's problems
The book's order: fiery gas, then a liquid ball with a burning atmosphere, then a cooled crust that wrinkled, then a hot ocean from the steam, then low lands and the first simple life. The author says we cannot know for certain how the earth was first made; geology cannot tell us.
Worked out for this site from the scan. If a number in your copy differs, trust the book.