CHANGED ROCK Rocks are hard materials made up of one or more minerals Metamorphic rocks are one of the three basic types of rock found on Earth The other two types are sedimentary and igneous Metamorphic rock forms from old igneous or sedimentary rock or other metamorphic rock Very high heat and great pressure Pressure is a weight or force that pushes down heavily on something It is caused by gravity Vocabulary Rocks make up Earth’s land surface The three main types from left to right are igneous metamorphic and sedimentary 4
inside Earth’s crust can change old rock into new metamorphic rocks The name metamorphic comes from Greek words meaning change of shape Most metamorphic rocks form slowly over millions of years They come in thousands of different shapes colors and sizes Many mountain chains are made of metamorphic rock People use metamorphic rock such as gneiss and quartzite to make building materials Slate is made into roofing People make statues and buildings from beautiful marble Metamorphic rocks are common in mountain ranges all over the world 5
REMAKING ROCKS Rocks are formed worn down and then formed again in a process called the rock cycle This means rocks can change into other types of rocks The events of the rock cycle can take place over millions of years The process depends on time temperature pressure and changes in conditions under Earth’s crust and at its surface The rock cycle is the process by which rocks of one kind change into rocks of another kind The events of the rock cycle can take place over millions of years Rocks can follow many paths through the rock cycle Vocabulary Mountains may look strong but they are being worn down into small rocks and sand every day 6
The crust is the outer layer of Earth The lower parts of this layer are solid rock or bedrock Broken bits of rock lie on top The smallest bits of rock make up sand and soil Underneath Earth’s crust is the upper mantle a thick layer of mostly solid rock Below that pools of melted rock or magma continuously move inside the lower mantle Magma is heated from the high temperatures in Earth’s core Magma is found in the part of Earth’s mantle called the asthenosphere 7
