Category Archives: Geology

What Are Igneous Rocks?

Igneous_rockIgneous rocks form when magma cools and solidifies. This happens both above and below the surface of Earth. Magma is made up of the atoms and molecules of melted minerals that rearrange themselves into mineral grains. When magma cools, rocks are formed. Magma can be forced into adjacent rocks, forced to the surface as lava, and also be blown out in volcanic explosions.

Over 700 different types of igneous rocks exist. Some of these types include granite, pumice, obsidian, tuff, and basalt.

Types of Igneous Rocks

Granite is a very common rock that contains 25% quartz and is commonly used in construction due to its strength and abundance.

Pumice is a very lightweight rock that forms when molten rock is quickly blown out of a volcano. As pressure is lost and the rock cools quickly, tiny bubbles (vesicles) are formed.

Obsidian is a volcanic glass that forms very rapidly without any crystal growth. Its edges are sharp and smooth making it a great choice for cutting tools or arrowheads.

Tuff is a rock formed from volcanic ash. During volcanic eruptions, rock, ash, and magma falls back onto Earth and is compacted and cemented into a rock, becoming a lens-shaped deposit called tuff.

Basalt is extremely common rock found all over our solar system. It is used in building materials and thermal insulators. When subjected to extreme heat and pressure over time it will metamorphosize into granulate.

 

The Science Behind the Age of the Earth

Geological_time_spiral How do you calculate your age? You simply go take out the difference between your birth year and current year, isn’t it? But when it comes to taking out the age of the sprawling sphere which we call home, Earth, it becomes a bit trickier. Let’s explore what science has to say about the age of the Earth.

The age of the Earth couldn’t be guessed by anyone before the process of radiometric dating came into play. In 1898, the pioneer of radiology, Marie Curie discovered the phenomenon of radioactivity. The atoms either decay or lose energy by emitting radiation in the form of electromagnetic waves or particles. Later, in the year 1904, Ernest Rutherford, the famous physicist determined how this decay could let them explore the age of old rocks.

With this exploration, Arthur Holmes, who was completing his geology degree in London, acted as a helping hand by developing a new technique of dating rocks using the uranium lead method. He applied this technique to the oldest rock and got to know its age. Applying the similar technique to calculate the age of the Earth made him reach the conclusion that the Earth was at least 1.6 billion years old.

But wait, this is not the actual age of the Earth! The Earth’s age has always been hotly debated among the scientists over the years. That is why several revisions have been made. Later, in 1920’s, an unknown scientist declared that Earth’s age was approximately 3 billion years. This suggested that the Earth was even older than the universe, which itself is 1.8 billion years old.

Later, the scientists declared that radiometric dating of the fragments from Canyon Diablo iron meteorite was the best estimate for calculating the age of the Earth. From those fragments, they got to know that the true age of Earth was 4.56 billion years.

Since then, scientists have been using radiometric dating to determine the age of extraterrestrial objects such as Earth, meteorites, space rocks and moon rocks. For many years, scientists have tried to determine the exact age and now that they have discovered its age using the radiometric dating, they are using it for several other space objects as well.

If you want to explore some more interesting information from the world of geology, come back and join us for more interesting information on other fascinating topics.          

Knowing What’s Underneath the Earth’s Surface

Breakaway view of the earth's inner cores
Breakaway view of the earth’s inner cores

Geology is an interesting subject as it involves studying different features of the earth including the oceans, mountains, rocks, earthquakes, and volcanoes.

Basically, a geologist studies all solid and liquid matter that forms the earth in addition to the history and processes that have fashioned it. A basic and important part of geology is the earth’s interior. This part of geology is what we’re going to discuss here.

Earth’s Interior

Just like the interior of your car, the earth’s interior is made up of a variety of elements and a number of layers are present in the earth’s interior. The earth’s crust, mantle, and the core are its major layers. The mantle is further divided into the upper and lower mantle while a liquid outer core and a solid inner core constitute the earth’s core.

The earth’s crust

The first layer of the earth consisting of about 16 kilometers of rock as well as unattached materials is known as the crust. Compared to its thickness under the oceans, the crust’s thickness underneath the continents is almost three times more.

The Earth’s Mantle

earth mantle cutaway viewMantle is the layer beneath the crust and accounts for a large majority of the Earth’s volume. Movements, know as convection in geology circles, is responsible for earthquakes and volcanic activity.  Almost 1,800 miles deep, the mantle consists of substances that are rocky, solid and thick. Of the earth’s total weight and mass, 85 percent is made up of this substance. Very hard, rigid rocks make up the mantle’s first few miles. Super heated solid rock makes up the next 100 or so. Solid and sturdy rock materials make up the next hundred miles of the earth’s mantle.

The Earth’s Core

Two layers that are mostly iron make up the earth’s core. Iron is estimated to make up about 90% of the earth’s core with oxygen, sulfur, or nickel combining to form the remaining 10 %. The earth’s core consists of mostly iron and nickel. Solid, the earth’s inner core measures about 1500 miles in diameter.

The earth’s outer core also consists of mostly nickel and iron. The earth’s inner and outer cores combine to become as big as the planet Mars. Superheated liquid molten lava is what most people believe earth’s outer core is made of. A solid ball comprising mainly of nickel and iron is believed to make up the earth’s inner core.

There you have it—the earth’s interior and its components. The next time you start digging holes in your garden, you will know exactly what lies underneath it.