Earth Science Lesson #2 Earth’s Structure Name

_____________________________ •

Radioactive dating techniques provide data that indicates the Earth was formed approximately _________________ years ago. •As the Earth cooled, chemical reactions resulted in the production of the layers of the earth that exist today. These include a _______________ inner and outer core and a _____________ crust and mantle.


•The crust is the outermost layer of the Earth. It is also the ____________ layer and is divided into two types as shown below.

Continental Crust Oceanic Crust

35-70 km thick Up to 4 billion years old or over 3,500 million Up to 200 million years old Density about Up to thick Density about 3 g/cm 3 Igneous and sedimentary rocks Igneous rocks like gabbro and basalt

The crust is composed mainly of _________________, oxygen and aluminum.


•The mantle, the __________ layer of the Earth is just below the crust. The mantle has a thin, sedimentary layer of ___________ at the top, but under that is mainly magma. •Magma is __________ rock from the center of the Earth. The Mantle is hotter and denser because pressure inside the Earth increases with ____________. •The mantle is composed primarily of iron, ____________, aluminum and silicon.


•The core is nearly _____________ as dense as the mantle because its composition is metal (iron and ____________ ) rather than rocky. •The core is made of two parts, a liquid outer core and a solid inner core. •It is thought that the Earth’s magnetic field is created by the spinning of the liquid outer core as the Earth rotates.

Three Types of Rock Igneous Rock

    Formed at the surface from ___________ or formed inside the crust from __________ that has cooled. Examples: granite and basalt __________ cooling igneous rock (inside the earth’s crust), allows the formation of ____________crystals of individual minerals. (plutonic/intrusive) ______________ cooling igneous rock (outside the earth’s crust) has a ____________ texture with small crystals. (volcanic/extrusive)

Sedimentary Rock

   Formed from ___________ and erosion or from precipitated fragments that have been bound under pressure Examples: Limestone or _____________ Sedimentary rock is the most common source of ______________.

Metamorphic Rock

   Is formed under conditions of extreme temperature and ______________ change. Examples: Gneiss and marble Note: If too much temperature and pressure exist, the rock will __________ and become igneous.