Three Types of Rocks
All rocks are not the same, even though many of them look alike. There are three
main types or classes of rock: sedimentary, metamorphic, and igneous. The differences
between each of the rocks have to do with how they are formed. This is what
determines the type of rock it is.
The first type of rock is sedimentary. A sedimentary rock is formed from particles
of sand, shells, pebbles, and other pieces of material. All of these particles together
make up sediment. Sediment is the result of material broken down by weathering or
erosion.
Slowly, the sediment accumulates in layers and over a long period of time it will
harden into rock. Sedimentary rock, usually, is fairly soft and may break apart very
easily or crumble into pieces. If sedimentary rock is broken apart inside is sand,
pebbles, or stones in the rock. Sedimentary rock is usually the only type of rock that
also contains fossils. Fossils are the remains of once living animals or plants usually
from long ago.
Examples of sedimentary rock types include limestone, shale, and sandstone.
The second type of rock is metamorphic. A metamorphic rock is formed under the
surface of the earth from the change that takes place because of intense heat or
pressure. In nature, it takes millions of years for a metamorphic rock to be formed. The
rocks that result from this very long process often has ribbon-like layers and many
shiny crystals. The crystals are formed by minerals which grow slowly over time on the
surface of the rock.
Examples of metamorphic rock types include gneiss, marble, slate, and quartzite.
The third type of rock is igneous. Igneous rocks form when magma cools and
hardens. Magma is the molten rock deep within the earth. The same material inside a
volcano. Sometimes this magma, though, cools inside the earth. At other times it will
erupt onto the surface from a volcano. When magma leaves the volcano, it is
called lava.
When this lava cools very quickly, no crystals form and the rock will look shiny and
glasslike. Sometime there are gas bubbles trapped inside the rock during the cooling
process of the magma. If this occurred there will be tiny holes and spaces left in the
rock.
Examples of igneous rock types include basalt, obsidian, pumice, and granite.
In summary, even though many rocks may look alike, there are three types of rocks
with different characteristics. The three types of rocks are sedimentary, metamorphic,
and igneous. Sedimentary are form from sediments that may include particles of sand,
pebbles, or other stones. Fossils may also be found in sedimentary rock. Metamorphic
rock takes millions of years to form and is formed by intense heat and pressure. They
often are ribbon-like and contain shiny crystals. The last type is igneous rock, which
forms when magma cools and hardens deep inside the earth. Magma is the same
material inside of a volcano. All three rock types can be found in many places. Some
examples of each include limestone, marble, and granite. Rocks are definitely not all
the same.
Living and Non-Living Things
The world is made up of many different things. Some of the things are living and
others are non-living. A dog, swing set, car, tree, flowers, and a book are some of the
things that make up the world.
There are two different kinds of things in the world. One kind is called living
things. Living things eat, breathe, grow, move, reproduce and have senses. The
other kind is called nonliving things. Nonliving things do not eat, breathe, grow,
move and reproduce. They do not have senses.
An example of a living thing in the world is a dog. A dog is an animal, and dogs need
food, water, space, and shelter. The dog is a living thing. A tree or flower is a plant,
and trees and flowers need air, nutrients, water, and sunlight. A flower and tree are
also living things. Plants are living things and they need air, nutrients, water, and
sunlight. Other living things are animals, and they need food, water, space, and shelter.
A dog eats food, breathes in air, and grows from a puppy to a dog. A dog
reproduces. Reproduce means to make one of its own kind. A dog also has
senses. Senses are seeing, hearing, smelling, tasting, and feeling.
Other living things include people, cats, rabbits, bugs, lions, and many others. There
are many different kinds of plants, too. Plants can include dandelions, grass, corn,
tomatoes and much more.
Non-living things include things that do not need food, eat, reproduce, or breathe. A
car does not eat or grow. It does not move unless a person is driving it. It does not
need air to breathe and it has no sense. It is a non-living thing. A swing set does not
use food. A book does not move. The swing set and book do not grow, and they do not
need air to breathe. They are non-living things. Nonliving things do not need air, food,
nutrients, water, sunlight, or shelter. Other non-living things in the world include
pencils, rocks, footballs, toys, hats, and many others.
One more example of a living thing is a bird. A bird eats seeds or worms. It breathes
in air. It comes from an egg and grows. It moves by flying. It lays eggs and
reproduces. It smells and sees because it has senses. A bird is a living thing.
One more example of a non-living things is a ball. A ball does not eat anything. It
does not need to breathe. It never grows. It never moves unless a person throws or
rolls it. The ball does not reproduce. It cannot hear or feel, and it has no senses. A ball
is a non-living thing.
In summary, everything in the world is a living thing or a non-living thing. Living
things can be plants which need air, water, nutrients, and sunlight. Living things can be
animals which need food, water, space, and shelter. There are living things and
nonliving things everywhere. Living things eat, breathe, grow, move, reproduce and
have senses. Reproduce means to make one of its own kind. The senses are seeing,
hearing, smelling, tasting, and feeling. Nonliving things do not eat, breathe, grow,
move and reproduce. They do not have senses. A dog and tree are living things. A book
and a car are nonliving things.
Biomes
Biomes are large ecosystems divided into six areas across the Earth.
The taiga biome is located in the mid- to high latitudes. Its climate is very cold in
the winter, cool in the summer, and averages about 20 inches of precipitation a year.
The taiga's soil is acidic, very poor in minerals, and the surface is covered with dead
needles from pines and spruce. The spruce, fir and other evergreens makes up the
plant life. Animals include rodents, snowshoes, hares, lynx, sables, ermine, caribou,
bears, wolves, and birds.
The deciduous forest is located in the mid-latitudes with mostly a mild climate for
the summer and winter. The precipitation is usually around 30 - 50 inches per year. In
the deciduous forest, the surface is clay overlaid with top soil and allows for plant
growth such as oak, beeches, hickory, and maple trees. Living within the forest are
animals such as wolves, deer, bears, and a large variety of small mammals, along with
birds, amphibians, reptiles, and insects.
The tropical rain forest is located near the equator. The climate is hot year-round,
yet it averages between 80 - 180 inches of precipitation a year. In the tropical rain
forest, the nutrients in the soil is very poor. The tropical rain forest has the greatest
diversity in plant life than any other biomes which includes vines, orchids, ferns, and a
wide variety of trees. There are more species of insects, reptiles and amphibians than
any other place. There are also monkeys, other small and large mammals, including
elephants and all sorts of colorful birds.
The desert biome is located in the mid-latitude. Its climate is known for its very hot
days and cool nights. The precipitation averages around 10 inches a year. The plant life
consists of cacti, yuccas, bunch grasses, shrubs and a few trees. Rodents, snakes,
lizards, and tortoises, make up most of the animal life, but there are also insects and
some birds. The soil is poor with animal decay products but often rich in minerals.
Camels, gazelles, antelopes, small foxes, snakes, lizards, and gerbils all have their
home in the Sahara in Africa.
The tundra is located in the high northern latitudes. The climate is very cold, harsh,
and the winters are long. There are short and cool summers with an average
precipitation of 4 - 10 inches a year. The soil is nutrient-poor with a permafrost layer a
few inches underneath. In the tundra, plant life consists of grasses, wildflowers,
mosses, and small shrubs. The animal life consists of musk oxen, migrating caribou,
arctic foxes, weasels, snowshoe hares, owls, hawks, various rodents, and an occasional
polar bear.
The final biome is the grassland which is located in the mid-latitudes, within the
interiors of the continents. The climate is cool during the winter, and hot during the
summer with an average precipitation of 10 - 30 inches a year. The soil is a rich top soil
that supports plant life such as grasses, small shrubs, and trees near sources of water.
In the America Grassland the animal life consists of prairie dogs, foxes, small
mammals, snakes, insects, various birds. The Grasslands in Africa includes elephants,
lions, zebras, and giraffes.
In summary the six biomes include taiga, deciduous forest, tropical rain forest,
desert, tundra, and grassland. The biomes each have different climates, animals,
plants, and other characteristics.
The Water Cycle
The water cycle is the continuous movement of water between the surface of the
Earth and the air. The water cycle involves several steps involving evaporation,
transpiration, condensation, and precipitation. It is a continuous cycle where water
evaporates into the air and becomes part of a cloud, falls down to earth as
precipitation, and then evaporates again. This repeats again and again in a cycle that
lasts forever.
Evaporation is when the sun heats up the waters in oceans, lakes, and other bodies
of water. The water then changes into a gas. The water or moisture, now a gas, then
evaporates into the air. This continuously takes place all over the world.
Transpiration is the process by which plants lose water in the form of water vapor.
Transpiration is similar to evaporation by getting the water vapor from plants back up
into the air. It is also a part of the Earth's water cycle. It takes place continuously as
plants grow using the water that passes through the roots of the plants and is then
released into the air.
Condensation occurs when the water vapor in the air becomes cold and changes
back into a liquid. During the water cycle, clouds are formed due to condensation. It is
also condensation when water droplets from the air form on the outside of a cold drink.
Condensation also occurs following a hot shower. The water from the shower changes
to a water vapor and the droplets cover the mirror and other objects in the room.
Precipitation is rain, snow, sleet, or hail that falls to the ground. Precipitation
occurs during the water cycle when the air can no longer hold water that had been
evaporated. The clouds get heavy and the evaporated water falls back to the earth as
precipitation.
Rain forms in clouds when the clouds are large enough to have water droplets. The
water droplets collide and form raindrops. Snow is formed when water vapor changes
directly to a solid at a temperature of less than 32 F°. Sleet is basically rain drops that
freeze into ice pellets before reaching the ground. Hail is cooled water that freezes on
contact with ice crystals in clouds normally occurring in the summer months, and
usually during thunderstorms.
When precipitation ends up on the land it soaks into Earth and becomes ground
water. The ground water is then used by plants and animals for drinking. Groundwater
may be stored in aquifers. Aquifers are underground layers of rock that are saturated
with water. This can be brought to the surface through natural springs or by pumping.
If precipitation runs over the soil and collects in the oceans, lakes or rivers it is called
runoff. Runoff is the flow of water that occurs when excess storm water, meltwater, or
other sources flows over the earth's surface. Once this precipitation ends up in or on
the Earth's surface, the water cycle begins all over again.
In summary the Earth's water cycle continuously occurs throughout the world. The
four processes include evaporation, transpiration, condensation, and precipitation.
Precipitation is water that falls to the Earth through rain, snow, sleet, or hail. As the
water reached the Earth's surface it may become ground water stored in aquifers, or if
the Earth can no longer hold the water it becomes runoff. The water then flows back
into the Earth's different bodies of water.
States of Matter
Matter is basically a substance that takes up space. All matter is a solid, liquid, or
gas, and they are called the states of matter.
Everywhere a person looks, there are examples of solids: desks, chairs, windows,
rocks, tissues, and much more. Examples of liquids: water, milk, juice, chocolate syrup,
soda, and others. Examples of gases are harder to see because they are invisible: the
oxygen in the air, propane gas used for a grill, helium inside a balloon, and more.
Everything, all matter, can be identified as a solid, liquid, or gas.
Besides what they look like, there are many differences between solids, liquids, and
gases. These differences are called characteristics. The characteristics of each state of
matter are different. These characteristics determine if a substance is a solid, liquid, or
gas.
A solid has a definite shape. It can be hard or soft, smooth or rough. Solids can
come in all sizes. A solid can be large like the Statue of Liberty, or small like a marble.
It can be very tiny like a bread crumb, or as big as a mountain, and everything in
between. If small enough, solids can be held in a person's hand, and they are difficult
to compress or push, or change shape.
The molecules of a solid are compact and close together, and nearly impossible to
move through.
A liquid takes the shape of the container it is held in and will fill the bottom of a
container. Liquids usually have a smooth surface but does not have a specific size. A
person may be able to hold a small amount of liquid in their hand, but a liquid cannot
be held like a solid. Liquids are less difficult to compress or push. It is much easier to
move through a liquid than a solid.
The molecules of a liquid are spread out more than a solid, but less than a gas.
Finally, a gas has no shape, but can fill a container or any size or shape. It will fill an
entire container as the molecules move. A gas cannot be felt in the hands like a solid or
liquid. It has no surface or no particular size. It cannot be held in a person's hands, and
it is easy to push or compress. A gas is the easiest to move through versus a liquid or
solid.
The molecules in a gas are more spread out and move all the time. They are full of
energy.
Water is the best example of a substance that can be a solid, liquid, or gas. Water by
itself is a liquid. When water freezes it becomes a solid. If a container of water is
heated it turns into a gas called water vapor.
There are many other substances that can be more than one type of matter, too. Ice
cream is a solid until it melts, then it's a liquid. A moth ball is a solid, but it releases a
gas that a person can smell across the room.
In summary, the different states of matter are called solids, liquids, and gases. The
states of matter have different characteristics and examples of each can be found
throughout the universe.
The Layers of the Earth
The Earth is more than a giant ball made up of dirt, rocks, and minerals. The Earth
may look like a giant ball from when looking at it from the moon, and the surface may
be water, dirt, and other minerals, but deep inside the Earth there are four main layers.
These four layers of the Earth include the crust, mantle, outer core, and inner core.
The first layer most people are quite familiar with because they walk on it every day,
or maybe even dig holes into it. It is called the Earth's crust. The Earth's crust is the
outer layer of the Earth and is about 5 to 25 miles thick depending on its location. It is
the thinnest layer, only about 3-5 miles thick under the oceans which is called
the oceanic crust. Under the continents it is about 25 miles thick, which is called
the continental crust. The temperatures of the Earth's crust can be anywhere
between air temperature and 1600 F°, which is hot enough to melt the rocks inside the
Earth.
The thin layer of the crust is also broken into pieces called plates. The plates float
on top of soft mantle below the crust. The movement of these plates can cause
earthquakes to occur.
Two other areas of the Earth's layers are a part of the next layer, the mantle, and a
part of the crust. They are called the lithosphere and the asthenosphere. The
asthenosphere and lithosphere are mostly made up of rock types called granite and
basalt.
The second main layer of the Earth is called the mantle. The mantle of the Earth is
the largest layer and is about 1800 miles thick. It is made up of extremely hot, dense
rock and it flows like asphalt. The temperature at the top of the mantle is about 1600
F° and at the bottom it is about 4000 F°. Basically, the mantle is made up of melted
rock which allows the plates of the Earth's crust to float on top of it. When the melted
rock escapes to the Earth's surface, a volcano may erupt in that area of the Earth.
There are certain areas of the world where this is more likely to happen.
The final two layers of the Earth include the outer core and the inner core. The outer
core is basically made up of melted metals, nickel and iron. Because these metals are
melted, they move just like a liquid. The outer core is located about 1800 miles below
the Earth's surface and is about 1400 miles thick. The outer core has temperatures
between 4000 F° and 9000 F°.
The inner core is about 800 miles thick and the temperatures may be as high as
9000 F°. There is so much pressure at this layer, the metals are squeezed tightly
together, and they are forced to vibrate as solids. The weight of the other layers of the
Earth is basically pressing down onto the inner core of the Earth.
In summary, the four main layers of the Earth include the crust, mantle, inner core,
and outer core. Two additional areas located between the crust and mantle are the
lithosphere and the asthenosphere. Earthquakes are caused by the movement of the
pieces of the Earth's crust called plates, and when a volcano erupts the melted rock
comes from the mantle of the Earth. Finally, the inner and outer core are the hottest
and deepest of the layers and are under the most pressure.