The World's Foundations; or, Geology for Beginners · Ch. XVII, part 2 · Unit 3: Part II: Reptiles, chalk, mammals, ice and people
19. The age of chalk: new trees and a great ending
Goal: Your child can describe how the Chalk Age changed plant life and explain what the book says happened at its close.
You'll need
- The book, open to this chapter
- A snail shell or a picture of a nautilus or ammonite
- Modeling clay (for an ammonite fossil)
- A notebook for a "rock journal" and a pencil
What's in the book
The second part of Chapter XVII (pages 161 to 168) describes the geography of the age, with Europe a collection of islands and the great mountain ranges still under the sea. Oak, beech, maple, fig, magnolia and other modern trees suddenly appear, the great reptiles and the ammonites come to their end, and a great break in life marks the close of the Middle-Life Period. It ends with a poem about the Nautilus and the Ammonite.
The lesson, step by step
A question to start
SayWhich trees grow near our home? Do you think they were here when the great reptiles lived?
Read to find out what the book says.
Read together
Read from the paragraph that begins "In America, although there is the so-called Chalk-formation" (page 161) to the end of the chapter (page 168). Sentences to stop on:
At the close of the Chalk Age, which is also the close of the Secondary Period, a great and remarkable destruction of life seems to have taken place.
Whether this destruction was sudden or gradual is a question about which opinions differ — the simple fact being that nobody knows.
Europe as islands
In plain words: during the Chalk Age, says the book, much of Europe was under the sea, more like a scattering of islands. The Alps, Pyrenees, Himalayas, Rocky Mountains and Andes were still under water or only just poking out.
New trees
Look at the book's list of trees found at Aix-la-Chapelle: oak, beech, sycamore, poplar, willow, walnut, myrtle, fig, maple, magnolia, holly, hickory and more. Have your child tick off the ones growing near your home.
The ammonite
Show the snail shell or picture. Ammonites were coiled shells, from an inch to a yard across, and they died out at the end of this age. Press the snail shell (or a coil of clay rope) into a flat lump of clay to make an "ammonite" fossil.
The poem
Read the poem by G. F. Richardson at the end of the chapter aloud. Its refrain echoes Chapter XII:
The Almighty's breath spake out in death,
And the Ammonite lived no more.
Ask which line your child likes best.
Tell it back
Ask your child to explain the two ideas in the book about the "break" between the Middle-Life and New-Life rocks: a sudden destruction of life, or missing layers. Which does the author think would be just as remarkable?
What we know now
Scientists now know what caused the great dying at the end of the Chalk Age, about 66 million years ago: a giant asteroid, about 6 miles wide, struck the earth where Mexico is today, and huge volcanic eruptions in India added to the harm. The change was sudden. The great mountain ranges rose later as the earth's plates collided; the Himalayas were pushed up when India crashed into Asia.
Afterwards
Notice it this week: find a magnolia, maple, holly or oak and remember that its family goes back to the Chalk Age. Let the clay ammonite dry and add it to the rock box.
Answers to the book's problems
One idea is that many animals died out suddenly; the other is that the change only looks sudden because layers from the time between have been washed away. The author says that such a huge, worldwide washing-away of layers would be at least as remarkable as a sudden destruction of life.
Worked out for this site from the scan. If a number in your copy differs, trust the book.