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.
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.
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)
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 ______________.
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.