How can geologists know that some particles in a certain soil came from another place? They do know stuff like that. Particles of rock from the Sierra Nevada Mountains are in the soils in the Central California Valley. Somehow, these particles, called alluvium (say "al-LOUV-ee-um") traveled hundreds of miles from their source.

How do you think they traveled? Do you think they got into the car and drove all day until they came to a nice place? Or maybe took a bus?

We'll find out.

After a heavy rain, each student can collect some muddy water running in the gutter or along the ground. Put the collected water into jars, and put on a sticker that tells where the water was collected.

There will be chunks (particles) of stuff in the water. Let the water sit in the jars for awhile, and the particles will settle. Unless some of the particles are materials that
float, such as wood particles.

Particles that settle can be called sediments (say "SEDD-ii- ments"), or alluvium.

Take a good look at the particles and see if you can tell what they are and where they were before they were collected.

There may have been a person down the street working in the garage, sawing wood. The sawdust may have fallen onto the driveway, and the rain washed it into the gutter. It washes down the street to the place where you collected it.

Maybe somebody poured oil into the gutter the last time he changed the oil in his car. (That is unlawful, because it pollutes the water table.) The rain comes along and begins to run along the gutter. Some of the oil goes with it, and gets collected, along with the other stuff that traveled with the water.

Moving water carries materials. That is how geologists know how sediments travel. They can test a soil sample and compare the particles to a rock far away, that is of the same type. Then they know that particles from the big rock fell off into a stream and traveled right along with the water.

A really fast-moving stream or river can even carry big rocks! Some rocks are heavier than other rocks. The lighter rocks can move farther and faster than the heavy rocks.

If we put garbage onto the ground, the rain-water run-off can carry the garbage into a stream, and it can travel great distances, polluting the water, all the way to the ocean. (This is unlawful, also!)

There is a half-boulder in Alaska and the other half is in Kansas. The brilliant geologists say they know it and it is true. Your brilliant writer does not know how to research
something like that, but perhaps your teacher does.