What are Sedimentary Rocks: Formation, Types, Fossils and Uses

Sedimentary rocks are one of the incredible secrets that lie beneath your feet. They are members of the three primary families of rocks on Earth. They appear in more places than you might think, but we hardly ever give them much thought. Sedimentary rocks include the coal used to power homes and the sand on the beach. These rocks took thousands of years to accumulate every layer. Although they may appear unremarkable at first, they are essentially nature's journal, documenting the lengthy history of the planet. So let's examine what makes them noteworthy.

Table of Contents

• How Nature Builds Sedimentary Rocks
• Interesting Facts About Sedimentary Rocks

How Nature Builds Sedimentary Rocks

Imagine a river flowing across the environment, gathering little stones, dirt and sand. All of that stuff has to land somewhere and it does; it sinks to the bottom of lakes, rivers, or the ocean. As the years pass, more material keeps piling on top. The upper layers push down hard on everything below them. Give it enough time, we're talking thousands of years and those squished-down layers eventually go solid. That's your sedimentary rock, right there. The particles that sink and settle are called sediments, which is exactly where the rock gets its name.

Interesting Facts about Sedimentary Rocks

Covering Most of Earth’s Land Surface

Sedimentary rocks take up roughly 75% of the Earth's land surface. This indicates that sedimentary rock makes up the majority of the ground you walk on every day. Sometimes it just appears to be flat slabs of sand, clay, or striped stone; you might not even recognize it as rock.

Layer Formation in Sedimentary Rocks

Finding the layers of a sedimentary rock, which scientists refer to as strata, is the simplest way to identify it. Each layer was developed at a distinct time. The more recent layers are at the top and the older material is at the bottom. Scientists are able to piece together what Earth looked like millions of years ago by reading these strata as if they were a book.

Fossils Hidden Inside Sedimentary Rocks

The majority of fossils found in museums were extracted from sedimentary rocks. This is because sediment can swiftly bury a dead plant or animal near water before it completely decomposes. It becomes trapped inside the hardening rock over an extended period of time and becomes a fossil. For this reason, experts researching ancient life find these rocks to be extremely valuable.

Different Kinds of Sedimentary Rocks

Sedimentary rocks aren’t all the same. They fall into three groups:

• Broken fragments of other rocks are used to create clastic rocks. Two rocks that form in this manner are sandstone and shale.
• When water containing dissolved minerals dries out and the minerals remain as a solid substance, chemical rocks form. One well-known example is rock salt.
• The remains of plants and animals are the source of organic rocks. For example, layers of dead plants that were buried underground and crushed over millions of years make up coal.

Uses of Sedimentary Rocks

Sedimentary rocks are useful to humans in a variety of ways; they don't just sit there looking ancient. Limestone goes into making cement. Coal keeps our lights on and our homes warm. Rock salt ends up in our kitchens. And petroleum, the stuff that gets refined into petrol and diesel, sits trapped between deep layers of sedimentary rock underground.

Formation over Millions of Years

There's no rushing this process. It takes hundreds of thousands to millions of years for sediments to pile up thick enough and press together hard enough to become actual rock. The rocks sitting around us today started forming long before the first human being ever walked the Earth.

The Role of Sandstone in Construction

In India, sandstone is probably the most familiar sedimentary rock. Red sandstone was used in the construction of some of the nation's most famous historical buildings, such as Delhi's Red Fort. Because it is durable, simple to shape and actually attractive, builders have always adored it.