Introduction

Hey this is cute.penguinz and we are blogging about plate tectonics and some other topics on Earth's geological features. We are posting about plate tectonics because we want other people who are interested to learn about earth science without having to read through a text book. We have posted different topics on plate tectonics and earth science and we also have fun games, videos, and the quiz. Check it out and have fun reading about earth science. Be sure to take the quiz after you finish reading! Have fun!

Mid Ocean Ridge

The Mid-Ocean Ridge is the longest mountain range on Earth. It is an underwater chain that gets bigger because of sea-floor spreading. Sea-floor spreading occurs around a divergent boundary in the ocean. It is when old sea- floor splits and lava comes up from the mantle and becomes hard. This is new sea floor. A divergent boundary is where two plates pull apart from each other. A plate is a piece of the earth's crust.

This is a picture of a mid- ocean ridge.

Convergent and Divergent Boundaries

Convergent and Divergent boundaries are boundaries that make different land forms such as mountains. Convergent boundaries are where two plates crash into each other. Plates move extremely slow so when plates are converging, they get slightly higher each year until a tall mountain is formed. While a mountain is being formed, the oceanic plate gets bent down. Divergent boundaries are where two plates separate. After the plates crack and separate, a block comes from underneath and the block has a hole filled with magma. The block sinks causing a central valley called a rift. Magma makes its way up to the Earth's floor and creates new land. This block filled with magma is called a volcano. From divergent bundaries, faults are formed from the spreading. Along the faults earthquakes occur very often. The constant movement of these boundaries often cause earthquakes and volcanoes.

This is a picture of a convergent boundary.

This is a picture of a divergent boundary.

California's Major Geologic Features

Major volcanoes in California include Mt. Shasta and Mt. Lassen. There also is a Mt. Saint Helens in Washington state. These volcanoes are there because California is part of the Ring of Fire. The Ring of Fire is the Pacific Plate and other major plates. Its constant movement causes many earthquakes and volcanoes. Major mountains such as the Sierra Nevada mountains and the Cascade Range exist also. Within the Cascade Range, there are many volcanoes. Mt. Saint Helens, as mentioned earlier, is one of them. It erupted violently recently. To view volcanic eruptions and mountains forming, see the video bar.

Above is Mt. Shasta, California.

Pangaea

Pangaea was a huge super-continent that existed 200 million years ago when the dinosaurs arrived. In 1915, Alfred Wegener purposed that Pangaea did exist. He thought this because matching fossils, coal beds and the same mountain ranges existed on many continents. Wegener was turned away because he didn't know how the continents moved. We now know that convection currents in the mantle move the plates and the continents move with them. The continents move one centimeter per year.  The plates are pieces of the Earth's lithosphere, or the crust. The crust is the top layer of the Earth, the one we live on.

The picture is a super-continent called Pangaea.

The Layers of the Earth

There are four layers of the Earth. The first layer (farthest away from the center of the Earth) is the crust. The crust is about 4 to 40 miles thick. Next is the mantle which is about 1,800 miles thick. After the mantle is the outer core. The outer core is about 1,300 miles thick. Last is the inner core which is about 1,500 miles thick. The inner core is also 1,200 miles in diameter. The crust is made up of a thin silicate rock material. The mantle is made up of a dark semi-liquid rock, rich in magnesium and silicon. Temperatures in the mantle can reach up to 6,692 degrees F, and 3,700 degrees C. The outer core is made up of a liquid molten core of nickel and iron. The inner core is made up of solid metal, iron. The inner core reaches 1,200 kilometers in diameter. The temperature of the core reaches temperatures hotter than the sun!

This picture shows the Earth's layers.

The Ring of Fire

The ring of fire is a chain of volcanoes that formed on or near the borders of the continents Asia, North America, Australia, and South America. It doesn't really look like a ring; in fact, it looks more like a horseshoe. It has 452 volcanoes in total, and it has 75% of the world's dormant volcanoes. Also contributing to this is that most of the world's earthquakes have occurred here or in places close to here. The ring of fire also is a great subduction zone area. Many mountains have formed in this place.


This is a picture of a map with the ring of fire.