Science 20 Unit C Earth

5/6/2009

Science 20 Unit C – Earth Name: ______

Raising the Rockies Date: ______

Complete this notes handout by reading the sections indicated and filling in the blanks or answering the questions as required.

We have looked at plate tectonics and the moving crustal plates as the force behind earthquakes. Today, you will learn more about the idea of plate tectonics.

Evidence for Plate Tectonics

(Read Paleomagnetism on pages 300-301.)

Many rocks have magnetic properties. The rocks gain these properties from being placed in the Earth’s magnetic field. A magnetic field will show the direction a magnetic force will act in (i.e. it will show the north and south pole of a magnet).

Evidence in rocks have shown that the Earth’s magnetic field has changed position over the history of the Earth, reversing every several million years. This leads to patterns in the magnetic fields of the rocks on the ocean’s floor.

Re-create Figure C1.8 of the magnetic field lines on the ocean’s floor below.

When geologists study the magnetic fields in rocks at different locations, they notice the same pattern often occurs at different locations. This is evidence that the ocean floor is ______apart. The study of these magnetic patterns is called ______.

Further evidence for plate tectonics is the formation of a large super content. Read “Further Evidence for Plate Tectonics” on pages 354-355 and fill in the blanks below.

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Geologists believe that through plate movement, the continents formed one large land mass called ______. This process began in the ______period, approximately ______million years ago.

The process continued into the ______period when large swamps covered most of what is now North America. This vegetation was later turned to ______which we now mine today. Also present in this period for the first time are small ______.

Following the Carboniferous Period, reptiles began to diversify well into the next period, the ______Period.

Life on Earth often followed cycles of flourishing and extinction. The graph below shows the percentage of marine species made extinct over the period of 500 million years.

Practice Problem: From the graph to the left, you can see 6 mass extinctions, labeled A-F. Using the geologic time scale found on page 312 of your textbook or on page 4 of your data sheet, determine which period each letter marks the end of.

A: end of the ______Period.

B: end of the ______Period.

C: end of the ______Period.

D: end of the ______Period.

E: end of the ______Period.

F: end of the ______Period.

While the causes of these extinctions is not precisely known, scientist have some theories. Read “Causes of the Permian Extinction”, “The Effects of Volcanoes” and “The Mesozoic Era”, then complete the summary below.

Possible Causes of the Permian Extinction:

Cause 1: ______

How it could have caused mass extinction:

______

Cause 2: ______

______

Cause 3: ______

______

Cause 4: ______

______

Building the Rockies:

Read page 358 and fill in the following blanks.

The Rocky Mountains began to be formed in the mid ______Period due to the continual break-up of ______. At this time in Earth’s history, Alberta was on the coast of the North American continent, and present day British Colombia, Alaska and the western USA made up a land mass called the western ______.

Tectonic plate movement caused the western island plate to be ______under the North American plate. The edge of the North American plate was ______, ______and thrusted to the east. The continents welded together forming the Rocky Mountains. At the time this was occurring, the mountains would have been the site of natural phenomenon like ______and ______.

The weight of the mountains caused the Earth’s surface to ______, allowing ocean water to flow inland creating a large ______. Sediment from the mountain formation flowed into this body using the ______and ______Periods, creating deltas, swamps and forests that became home to dinosaurs and mammals.

As the sea gradually uplifted and drained, the existing mountain range continued to increase in height, and the mountain range became even higher.

Practice Problems: Page 362

#19 (hint: check out #2 on page 352 for help)

#20 (hint: look at Figure C2.53)

#23.a) b) c) d) e) f)

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