Briefly describe what you believe is earth’s history. Warm Up: on p.1 What is history? Briefly describe what you believe is earth’s history. 3rd Quarter Notebook Date Session # Activity Page 1/12-13 1 Earth History Earth Forces and Composition Review 2 Homework: Study for test next class period Review session Friday am Please take your rainboots, etc. home!!

8.E.2 Understand the history of Earth and its life forms based on evidence of change recorded in fossil records and landforms. 8.E.2.1 Infer the age of Earth and relative age of rocks and fossils from index fossils and ordering of rocks layers (relative dating and radioactive dating) 8.E.2.2 Explain the use of fossils, ice cores, composition of sedimentary rocks, faults, and igneous rock formations found in rock layers as evidence of the history of the Earth and its changing life forms familiar and unfamiliar terms……add to vocab

TLW review forces and composition involved in shaping earth’s history by modeling the rock cycle with playdoh, closely reading an article & diagram, complete text questions & completing a quick write explaining earth’s consistent size.

Using clay and the expo marker, create the rock cycle on your white board. Use the expo marker for the arrows. Label the processes the arrows represent. Create an accurate model of the different stations in the rock cycle using the clay.

tape onto page 2 color code color code….igneous rock and processes that create it sedimentary rock and the processes that create it metamorphic rock and preocesses that create it color code

Label: oceanic crust, continental crust, mantle, inner core, outer core Don’t label these lines yet!!

Crust Continental Crust: thicker, less dense, older Oceanic Crust: thinner, more dense  

 Mantle: thickest layer, hot rock, convection currents that move tectonic plates  

 Core Outer Core: liquid, circulates around the inner core, iron & nickel Inner Core: solid, iron The circulation of the liquid outer core material around the inner core causes earth’s magnetic field

Read and annotate: 1st read: What surprised you 2nd: Relationship between layers. sticky note cover over article, diagram first

Crust and Mantle vs. Lithosphere and Asthenosphere   Why do we use two names to describe the same layer of the Earth? Well, this confusion results from the different ways scientists study the Earth. Lithosphere, asthenosphere, and mesosphere (we usually don't discuss this last layer) represent changes in the mechanical properties of the Earth. Crust and mantle refer to changes in the chemical composition of the Earth. Lithosphere and Asthenosphere The lithosphere (litho: rock; sphere: layer) is the strong, upper 100 km of the Earth. The lithosphere is the tectonic plate we talk about in plate tectonics. The Asthenosphere (a: without; stheno: strength) is the weak and easily deformed layer of the Earth that acts as a “lubricant” for the tectonic plates to slide over. The asthenosphere extends from 100 km depth to 660 km beneath the Earth's surface. Beneath the asthenosphere is the mesosphere, another strong layer. Read and annotate 1st: scan article for unfamiliar terms. 2nd: read for what the author thought you already knew 3rd: read for surprise

Describe the components of the Lithosphere; use evidence you see in the diagram to support your answer. Describe the characteristics of the Mantle, use evidence you see in the diagram to support your response.

The earth is broken into plates that move….how do we know?

Alfred Wegener’s Evidence Wegener noticed that earth’s continents appeared to fit together like a puzzle. He hypothesized that they were once joined as a single landmass – Pangaea Evidence: Mesosaur fossils in S. America and W. Africa – nowhere else in the world Climate: tropical plant fossils found in Greenland, near the arctic circle, and Antarctica. South African rock formations show evidence of ice sheet scratches Geology: rock layers in Brazil match those in W. Africa. Appalachian Mtns have limestone similar to Scotland’s Highlands

Harry Hess - Sea Floor Spreading Scientists mapping ocean floor found huge underwater mountain ranges—Mid Ocean Ridges Ridges form along cracks in the crust. Molten rock rises through crack, forms new crust, older material is pushed away from the crack. Ocean trenches found on sea floor. Oceanic crust sinks under continental crust and melts into asthenosphere. Drilling samples of sea floor reveal youngest rock is closed to the ridge, oldest is further away. Oldest ocean floor is younger than continental crust. Magnetic Reversals of earth’s magnetic field preserved in rocks.

Magnetic Reversals Minerals in magma rising through the mid ocean ridge align themselves with earth’s magnetic pole As the rock cools, the minerals stay fixed in this position, like a compass Earth’s poles periodically reverse. The “stripes” of rock along the ocean floor record these reversals.

Why does the size of the earth remain relatively constant? page 1 Why does the size of the earth remain relatively constant? Using information reviewed in class today, explain why the size of the earth remains relatively constant. (circumference, diameter)