Archeologists are scientists who study the remains of past civilizations. They reconstruct the past by gathering clues. Bones are one kind of clue. Artifacts and fossils are other clues. Artifacts are objects from the past, usually made by people. Fossils are impressions or remains of animals and plants that have turned to stone. Archeologists begin to collect evidence at a spot where people might have lived and worked. Scientists begin to clear away layers of earth to find signs of human civilization. Archeologists call this spot a site, or dig.
Archeologists remove each layer by hand, using many kinds of tools, from shovels to dentist instruments. They work very slowly because they do not want to damage the delicate artifacts and fossils buried in the soil. Workers sift the dirt and rubble through a sieve. They look for things like bits of pottery, tools, seeds, weapons, and bones.
Archeologists record the exact location of every item they find. Then they use high-tech equipment to determine the age of each item. Archeologists must know as much as possible to identify artifacts.
Answer the questions below
|are the impressions or remains of animals and plants that have turned to stone.|
|Bones, fossils, and are clues used by archeologists.|
|Objects from the past, usually made by people are called .|
|The or dig, is the spot where archeologists begin to collect evidence.|
|A is used to sift sand and rubble.|
|Archeologists reconstruct the past by gathering .|
|This passage says archeologists search for pottery, tools, seeds, weapons, and .|
|The type of equipment used to determine the age of an item is|
|a sieve. a camera.|
Life on a Glacier
Is there life on a glacier? Of course there is!
The surface of a glacier is a jumble of rock and dirty snow which has been folded and contorted by stress. If you look at it up close it looks like a barren wasteland. What could possibly live there?
The wind is responsible for bringing life to the glacier. As wind moves over land, it gathers bits of dust and debris. When the wind sweeps over the glacier it deposits part of the load. Tiny insects such as spiders, beetles, and flies, grains of pollen from flowers, and minerals are mixed in with the dust. As these are spread over the snow and ice, they become a feast for tiny creatures such as the snow flea. The snow flea is a tiny insect that crawls around on the glacier in search of pollen.
Another creature which exists on a glacier is the ice worm. It is a relative of the earthworm, but less than an inch long. It lives hidden in the cold glacial ice. Ice worms wriggle between ice crystals near the glacier's surface, but sometimes can be found as deep as six feet. Ice worms burrow into the glacier's ice during the heat of the day and inch to the surface around dusk to feed. They depend mainly on the wind to bring their dinner of pollen and other plant materials.
Ice worms can survive only under certain conditions. Temperatures around freezing (32 degrees F.) are perfect. If they get caught in the sun's heat where it is warmer than 40 degrees F., they will die. When the ice around them freezes solid and becomes colder than 22 degrees F., their bodies freeze. Therefore, ice worms are found only in glaciers near the ocean, or where the climate is warm enough for melt water to be in the ice at all times.
A special algae that grows on the surface of the snow provides food for the ice worm. Snow alga is a type of green alga. Its color is red, which provides a screen against the bright rays of the sun.
Birds flying over a glacier feed on ice worms and insects, plucking them from the ice. Other animals use glaciers as a temporary home and a resting place.
Answer the questions below
|The main idea of this passage is:|
|Ice worms are found only in glaciers near the oceans. Many forms of life exist on a glacier.|
A glacier is a temporary home for animals.
|The is responsible for bringing life to a glacier.|
|The ice worm is a relative of the .|
|A snow flea feeds on deposited by the wind.|
|Ice worms are found only in glaciers near the , or where the climate is warm enough for melt water to be in the ice at all times.|
|An ice worm can be found six beneath the surface of a glacier.|
|pluck ice worms from the ice.|
|Perfect conditions for an ice worm's survival is|
|22 degrees F. 32 degrees C. 32 degrees F.|
|Snow alga is|
|red in color. green in color. colorless.|
|Some animals use a glacier as a home.|