Read the selection and choose the best answer to each
question.
What Makes Up the Earth's Crust
by Agnes Giberne
1 People tend to think of land and water on the earth as if they were fixed in one changeless form. As if every continent and every island were of exactly the same shape and size now that it always has been and always will be.
2 Yet, nothing can be further from the truth. The earth's crust is a scene of constant change, struggle, building up, and wearing away.
3 The work may go on slowly, but it does go on. The sea is always fighting against the land, beating down her cliffs, eating into her shores, swallowing bit by bit of solid earth. Rain and frost and streams are always busily at work. They help the ocean in her work of destruction. Year by year and century by century, it continues. Not one country in the world, which is bordered by the sea, has the same coastline that it had one hundred years ago. Every land loses a part of its material every century. It is washed away, bit by bit, into the ocean.
4 Is this hard to believe? Look at the crumbling cliffs around old England's shores. See the effect upon the beach of one night's fierce storm. Mark the pathway on the cliff, how it seems to have crept so near the edge that here and there it is scarcely safe to walk upon. Very soon, such a path will become impassable. Just from a mere accident, of course, the breaking away of some of the earth, loosened by rain and frost and wind. But, this is an accident that happens daily in hundreds of places around the world.
5 Leaving the ocean, look now at the river near your own neighborhood. See the slight muddiness which seems to color its waters. Why is that? Only a little earth and sand are carried off from the banks as it flowed. It is very unimportant, and small in quantity, doubtless, just at this moment and just at this spot. But what of that little going on week after week, and century after century, throughout the whole course of the river, and throughout the whole course of every river in our whole country and in every other country? A vast amount of material must every year be torn from the land and given to the ocean. And the land's loss here is the ocean's gain.