Mud
Mud is dirt and water mixed. It is very squishy. People use it to build houses. Animals use it to stay cool. It can be fun to play in. Have you ever played in mud?
Early Reader · Change the reading level on the articleEarth Science articles — Page 21
Explore rocks, volcanoes, weather, oceans and the processes that shape Earth. Choose an article below; its reading controls let you move between the available levels.
1,427 public articles · Page 21 of 30
Mudcrack
Wet mud can dry up. It gets smaller as it dries. This makes cracks in the ground. The cracks look like shapes. You can see them in dry ponds. Do you like to look at them?
Early Reader · Change the reading level on the articleMudflat
Mudflats are wet lands by the sea. The water comes in and goes out. This happens twice every day. Many birds and fish live there. They need the mud to find food. It is a busy place! Have you seen a mudflat?
Early Reader · Change the reading level on the articleMudflow
A mudflow is moving dirt. It happens when lots of water mixes with soil. The mud moves fast down a hill. It can push things out of its way. We must stay safe from it. Have you ever seen wet mud?
Early Reader · Change the reading level on the articleMudrock
Mudrocks are made of tiny bits of earth. These bits are very small. They can be in lakes or oceans. Some mudrocks turn into hard stone. This stone helps us make things. Do you like playing in the mud?
Early Reader · Change the reading level on the articleMuscovite
This rock is made of thin sheets. It can look clear or colored. Some sheets are very thin. You can use it for windows. It is a pretty thing to see. Do you like shiny rocks?
Early Reader · Change the reading level on the articleMylonite
Some rocks change deep in the ground. They get squeezed and pushed. This makes the tiny parts very small. These rocks look very tight. It is a neat way to make a rock. Can you find a rock?
Early Reader · Change the reading level on the articleNamib
The Namib is a big desert. It is by the sea. It has very tall sand dunes. The desert is very dry. Some plants and bugs drink fog to get water. Can you imagine living in a place with no rain?
Early Reader · Change the reading level on the articleNankai Trough
Deep under the sea, there is a big dip. It is near Japan. The ground moves there. This can make the earth shake. It also holds gas for fuel. Can you imagine a world under the waves?
Early Reader · Change the reading level on the articleNative copper
Copper is a shiny metal. It is found in the ground. It can look red or brown. It can even turn green. People have used it for a long time. It is very special. Do you like shiny things?
Early Reader · Change the reading level on the articleNative element mineral
Some things are found all alone. They do not mix with other things. Gold and silver are like this. They stay pure in the ground. This helps us find them. Can you find gold?
Early Reader · Change the reading level on the articleNative metal
Some metals are found pure in nature. They are not mixed with other things. Gold is one of these metals. You can find gold in rocks. It is very special to find. Can you find a shiny metal?
Early Reader · Change the reading level on the articleNatural environment
The world is full of nature. It has rocks and water. It has air and life. Nature helps us live. We share it with animals. Do you like the outdoors?
Early Reader · Change the reading level on the articleNatural hydrogen
Earth makes its own gas. It stays deep under the ground. This gas can help us make power. It helps us light up our homes. It is a big find! Do you want to see it?
Early Reader · Change the reading level on the articleNatural logarithm
Math uses a special rule. It helps us find big numbers. It can also help with money. This rule is very useful. It helps us learn. Do you like math?
Early Reader · Change the reading level on the articleNazca plate
A big piece of the sea floor moves. It is under the blue water. It pushes under the land. This makes tall mountains. The moving ground can make the earth shake. It is a busy place! Can you feel the ground move?
Early Reader · Change the reading level on the articleNear-surface geophysics
People can see under the ground. They use tools to look deep. These tools find old things. They can find buried pipes too. It helps us learn about Earth. Do you want to look under the dirt?
Early Reader · Change the reading level on the articleNenets Nature Reserve
This is a special place for nature. It is by the sea. Many birds fly here to rest. Big walruses live here too. It is a safe home for them. Do you like birds?
Early Reader · Change the reading level on the articleNeoarchean
A long time ago, the Earth changed. New land began to form. Tiny life grew in the water. The air started to change, too. This helped new life live. It was a busy time! Can you imagine the old Earth?
Early Reader · Change the reading level on the articleNeoproterozoic
A long time ago, Earth was very cold. Huge sheets of ice covered the world. This was called Snowball Earth. Some new life began to grow then. Small animals lived in the sea. It was a big change for our world. Can you…
Early Reader · Change the reading level on the articleNeptune's Grotto
This is a big cave. It is by the sea. You can walk down many steps. It has a salt lake inside. People like to visit it. Do you like caves?
Early Reader · Change the reading level on the articleNeritic zone
The ocean has shallow parts. Sunlight reaches the bottom here. This light helps plants grow. Many fish and sea life live here. It is a busy place for animals. Do you like the sea?
Early Reader · Change the reading level on the articleNevado de Toluca
This is a big mountain in Mexico. It is a volcano. It has two blue lakes at the top. It can be very cold there. Snow may fall on the mountain. Do you like the cold?
Early Reader · Change the reading level on the articleNevado Sajama
Sajama is a very big mountain. It is in a place called Bolivia. The top has white ice on it. Some small trees grow there too. It is a very special place. Do you like big mountains?
Early Reader · Change the reading level on the articleNicolas Desmarest
Nicolas was a man who loved rocks. He walked a lot to see the Earth. He found out how old lava was. He saw how rivers make valleys. He helped us learn about our world. Do you like to look at rocks?
Early Reader · Change the reading level on the articleNicolas Steno
Nicolas was a smart man. He looked at rocks and bones. He found out how they form. This helps us learn about Earth. He was a great helper. Do you like to look at rocks?
Early Reader · Change the reading level on the articleNimbostratus cloud
A dark cloud fills the sky. It brings rain or snow. This rain can last for a long time. It does not bring loud thunder. It helps the plants grow. Do you like the rain?
Early Reader · Change the reading level on the articleNitrogen cycle
Air has a special thing in it. It helps plants grow big. Tiny bugs in the dirt change it. Then plants can use it for food. It helps all life on Earth. Can you find it in the air?
Early Reader · Change the reading level on the articleNoctilucent cloud
Some clouds glow at night. They are very high up. They are made of tiny ice. You can see them in summer. They look so pretty! Have you seen a glowing cloud?
Early Reader · Change the reading level on the articleNodule (geology)
A nodule is a small rock lump. It looks like a round knot. It can be inside other rocks. These lumps have bumpy skin. They can be found on the sea floor. Can you find a bumpy rock?
Early Reader · Change the reading level on the articleNorth American plate
The ground under us is a big piece. It holds much of North America. It moves a tiny bit each year. This piece of land is very large. It is the second largest piece. We live on it! Can you feel the ground move?
Early Reader · Change the reading level on the articleNorth Aral Sea
A big lake is growing back. It is called the North Aral Sea. A river feeds the water. Now, many fish live there again. This helps the people who fish. It is good to see the water rise. Do you like lakes?
Early Reader · Change the reading level on the articleNorth magnetic pole
The Earth acts like a big magnet. It has a special spot in the north. This spot moves all the time. It helps us find our way. A compass needle points to it. Do you like using a compass?
Early Reader · Change the reading level on the articleNosean
Some rocks have special bits in them. This one can be blue or green. It can even glow in the dark. You can find it in many places. It is a rare find. Do you like bright colors?
Early Reader · Change the reading level on the articleNubian Sandstone Aquifer System
There is a lot of water underground. It is under the hot desert. This water helps people grow food. It is very far down in the sand. We can use it to live. Do you like water?
Early Reader · Change the reading level on the articleObsidian
Obsidian is a dark rock. It comes from hot lava. The lava cools very fast. This makes it look like glass. It has very sharp edges. People used it to make tools. Can you find a sharp stone?
Early Reader · Change the reading level on the articleOcean acidification
The ocean is changing. It takes in air from above. This makes the water different. It can be hard for sea life to grow shells. This matters to many people. Can you help the ocean?
Early Reader · Change the reading level on the articleOcean dynamics
The ocean water moves in many ways. It has a top part near the air. This part can be warm. Deep down, the water is cold and dark. The water moves slowly in the deep. It is a big, busy world! Do you like the sea?
Early Reader · Change the reading level on the articleOceanic basin
Big parts of Earth are under the sea. These are called ocean basins. They hold almost all the water on our world. Most of them are very deep. They help us live. Do you like the ocean?
Early Reader · Change the reading level on the articleOceanic crust
The ocean floor is made of rock. It is under the deep blue sea. This rock is very heavy. It is thinner than the land. It stays under the water. It is a big part of our world. Do you like the sea?
Early Reader · Change the reading level on the articleOceanic zone
The deep ocean is very big. It is far from the land. Some parts are very dark. Some fish make their own light. It is a cool place to see. Do you like the sea?
Early Reader · Change the reading level on the articleOcean surface topography
The ocean is not flat. It has hills and valleys. These hills move the water. They help us see how the ocean flows. This helps us know the weather. Can you imagine a hill in the sea?
Early Reader · Change the reading level on the articleOcean temperature
The ocean can be warm or cold. It is warm on top. It is very cold deep down. This helps fish live in the sea. The water is getting warmer now. Do you like to swim in the sea?
Early Reader · Change the reading level on the articleOchre
Ochre is a color from the earth. It comes from clay and sand. It can be yellow or orange. It can even be red. People use it as paint. Long ago, people used it for art. Do you like these colors?
Early Reader · Change the reading level on the articleOgallala Aquifer
There is a lot of water under the ground. It stays in the sand and rocks. Farmers use it to help plants grow. We need to be careful with it. It takes a long time to fill back up. Do you like to drink water?
Early Reader · Change the reading level on the articleOjos del Salado
This is a very tall mountain. It is a sleeping volcano. It sits between two lands. It is the highest volcano on Earth. It has a small lake at the top. Can you imagine climbing it?
Early Reader · Change the reading level on the articleOkhotsk plate
The ground moves in big pieces. These pieces are under the sea. Some pieces move and shake. This can make the land shake. It helps us learn about our world. Do you want to see more?
Early Reader · Change the reading level on the articleOld Faithful
A hot spring shoots water high. It is in a big park. It is very good at its job. You can wait for it to pop. It is a fun thing to see. Do you like to watch water?
Early Reader · Change the reading level on the article