ALPHA COLLEGE OF ENGINEERING AND TECHNOLOGY CIVIL A [3RD SEM ] TOPIC :- TYPES OF ROCK AND ROCK CYCLE GROUP 1O ENROLLMENT NO DARSHAN R MEHTA 130510106032 KOMAL N MALVANIYA 130510106030 HARDIK G MAKWANA 130510106029

Rocks and The Rock Cycle

What is a rock? A rock is a mixture of such minerals, rock fragments, volcanic glass, organic matter, or other natural materials. Most rock used for building stone contains one or more common minerals, called rock-forming minerals, such as quartz, feldspar, mica, or calcite When you look closely, the sparkles you see are individual crystals of minerals.

How do Rocks form? How much time does it take to form a rock? If you squeeze and heat a rock for a few million years, it can turn into a new kind of rock.

Continued… Where does the heat come from? When rocks are close enough to the magma to be heated but not close enough to be melted, the rocks can be changed.

Continued… Where does the pressure come from? Rocks below the surface are squeezed by the layers of rock above them. The thicker the layers, the more pressure there is.

What makes up the earth?

3 Main Rock Types Igneous Sedimentary Metamorphic

THE THREE TYPES OF ROCKS Igneous rock is formed from molten rock that has cooled and hardened. Sedimentary rock is formed from material that has settled into layers and hardened. Metamorphic rock is a rock that has changed by heat and pressure.

Examples… Igneous Metamorphic Sedimentary Granite Slate Sandstone Obsidian Marble Limestone Pumice Gneiss Shale

IGNEOUS ROCKS Form by solidification (crystallization) of melted minerals At the surface, LAVA hardens to form EXTRUSIVE rocks with tiny (FINE-GRAINED) crystals or GLASSY (no crystal) TEXTURES Beneath the surface, MAGMA hardens to form INTRUSIVE rocks with easily visible (COARSE-GRAINED) crystal texture.

Granite Light-colored, coarse- grained, no pattern Mostly quartz, feldspar, mica, and hornblende Often used for buildings and monuments

Basalt Dark-colored, fine- grained, extrusive Formed where lava erupted onto surface Most widespread igneous rocks Found locally in the Palisades along west shore of Hudson River, Connecticut River valley

Gabbro Dark-colored, coarse- grained intrusive Similar composition to basalt—plagioclase feldspar with some pyroxene and olivine

Obsidian Natural volcanic glass Forms when lava cools very quickly Usually dark, but small pieces may be clear Fractures along curved (conchoidal) surface Used as spear and arrow points, knives

Pumice and other igneous rocks Light colored, frothy (many air spaces) Same minerals as in granite, but finer in grain size

Igneous Forms when lava cools quickly on the Earths surface EXTRUSIVE Forms from molten rock cooling and solidifying Magma cools slowly over millions of years deep beneath the surface INTRUSIVE

IGNEOUS---Extrusive Little or NO Crystals! Lava cools on the surface so fast mineral do not get a chance to form Extrusive rocks can be divided into two categories based on color Dark colors black-brown-red Basalt Obsidian Light colors white-gray-pink Rhyolite

IGNEOUS---Extrusive Little or NO Crystals! Lava cools on the surface so fast mineral do not get a chance to form Extrusive rocks can be divided into two categories based on color Dark colors black-brown-red Basalt Obsidian Light colors white-gray-pink Rhyolite

IGNEOUS---Extrusive Little or NO Crystals! Lava cools on the surface so fast mineral do not get a chance to form Extrusive rocks can be divided into two categories based on color Dark colors black-brown-red Basalt Obsidian Light colors white-gray-pink Rhyolite

IGNEOUS---Extrusive Little or NO Crystals! Lava cools on the surface so fast mineral do not get a chance to form Extrusive rocks can be divided into two categories based on color Dark colors black-brown-red Basalt Obsidian Light colors white-gray-pink Rhyolite

Igneous Forms when lava cools quickly on the Earths surface EXTRUSIVE Forms from molten rock cooling and solidifying Magma cools slowly over millions of years deep beneath the surface INTRUSIVE

IGNEOUS---Intrusive Large Interlocking Crystals!!! Magma cools slowly over millions of years… LARGE CRYSTALS FORM Intrusive rocks can also be divided into two categories based on color Dark colors black-brown-green Gabbro Light colors white-gray-pink Granite

3 Main Rock Types Igneous Sedimentary Metamorphic

Sedimentary Rocks Sedimentary rocks may be made of rock fragments—sediments—or by chemical reactions. The classification of sediments is shown below.

How to make a sedimentary rock Weathering and Erosion Transportation Deposition Compaction and Cementation Sedimentary Rock

Sedimentary Chemical Clastic Shale Sandstone Conglomerate Sedimentary rocks are divided into two categories Chemical Mineral are dissolved in to the water…water is evaporated off and leaves behind chemical sedimentary rocks Examples are Halite, Limestone and Gypsum Clastic Made from eroded fragments of other rocks Shale Microscope grains of mud cemented together Sandstone Sand grains cemented together Conglomerate Pebble to boulder size fragments cemented together

Clastic rocks–made of cemented sediments—are classified by their grain sizes.

Non-clastic rocks form by chemical precipitation (settling out from a solution.) Limestone is made from calcite, chert from quartz, and halite is rock salt.

Biologic sedimentary rocks come from the remains of organic matter. The most important of these is coal. Anthracite coal results from the greatest pressure and releases the most energy when burned. Other varieties are bituminous and lignite. “Petrified” (permineralized) wood is another organic rock.

More about sedimentary rocks Shale is the most common sedimentary rock Sedimentary rocks cover about three-quarters of the land surface For more about sedimentary rocks:

3 Main Rock Types Igneous Sedimentary Metamorphic

Metamorphic rocks form from HEAT&PRESSURE Two types of metamorphism Contact Rock surrounding a magma body get cooked and changes due Regional Tectonic forces Metamorphism occurs over a large area

Metamorphic Rocks Formed by heat and pressure changing existing rocks REGIONAL METAMORPHIC affects a large area and results from plate tectonics CONTACT METAMORPHISM affects rocks on a local scale, such as “baking” sedimentary rocks next to magma or lava

“Foliated” rocks contain much mica and other rocks that produce layering or banding Gneisses and schists are common in New York City and Westchester.

Non-foliated metamorphic rocks include marble, which comes from limestone, and quatzite, which comes from sandstone

Common Metamorphic Rocks Parent Rock Metamorphic Rock Granite Gneiss Shale Slate Sandstone Quartzite

What is the rock cycle? To show how rocks slowly change through time, scientists have created a model called the rock cycle. It illustrates the processes that create and change rocks.

Here is another version of the Rock Cycle

The Rock Cycle

The Rock Cycle explains how Rocks and Natural Processes are related weathering Sedimentary Metamorphic Is the rock cycle really this simple, neat and colorful? (NO) Created October 2, 2000, revised September 2001 melting pressure, heat Igneous

The Rock Cycle Sedimentary Igneous Metamorphic

Another Rock Cycle

Mohs Hardness Scale

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