Chapter 9 Section 3 Pgs SPI’s &

 In this section we will: 1. Describe the conditions needed for metamorphic rocks to form. 2. Explain how all rocks are linked by the rock cycle.

 Foliated  Metamorphic rock  Nonfoliated  Rock cycle

 Many conditions on Earth cause rocks to form and then to change  Low temperature processes (erosion and weathering)  High temperature conditions (molten rock, magma)  Pressures and temperatures increase as rocks are compressed or buried deeply  Grain sizes and chemistry are changed  Rocks also change when continents collide

 New rocks are formed when existing rocks are heated or squeezed but not melted  “change of form”  Rocks take on a whole new look after being exposed to extreme temperatures and pressures  Figure 21 pg 285

 New metamorphic rocks can form from any existing type of rock  Texture can be used to classify rocks  Texture differences in metamorphic rocks can be used to divide them into 2 main groups:  Foliated  Nonfoliated

 Foliated rocks: have visible layers or elongated grains of minerals  These rocks have been heated and squeezed into parallel layers  Many have bands of different-colored minerals  Examples include: Slate, gneiss, phyllite

 These rocks DO NOT have distinct layers or bands  Examples include quartzite, marble, soapstone  More even in color  Mineral grains do not appear to be arranged in any distinct pattern  Quartzite forms when quartz sand grains in sandstone re- crystallize after they are squeezed and heated

 Model scientists use to describe how different kinds of rocks are related and how rocks change from one type to another  The cycle can take MILLIONS of years  Figure 23, page 287

 If you pick any point on the cycle, you can see how that rock could become any other rock  The blob of lava that oozes to the surface forms igneous rock  Wind, rain, and ice wear away at it and it breaks into small pieces (sediment)  Sediment is carried by streams and rivers where it piles up over time  Weight above presses on sediment below  Mineral-rich water “glues” or cements it together  If the rock is buried deeply, pressure and heat inside Earth can change it to metamorphic rock

 What are two factors that can produce metamorphic rocks?  List some examples of foliated and non-foliated rock. Explain the differences in the two types of metamorphic rocks.  What is the difference between igneous and metamorphic rocks?  What does the rock cycle describe?