Week 4: Plate Tectonics Lab INTRODUCTION Since the plate tectonic revolution in

Question

Week 4: Plate Tectonics Lab

INTRODUCTION

Since the plate tectonic revolution in the late 1960's, our view of how the world works has changed drastically. Plate tectonics successfully explains how earthquakes, volcanoes and mountain belts form and how the continents and oceans have evolved with time. One of the most useful pieces of information are magnetic anomalies recorded in the ocean floor that allow us to determine rates and direction of sea floor spreading through time and to reconstruct past plate configurations. In this lab you will do several exercises to gain a better understanding of plate motion and rates.

Plate Reconstructions

The evolution of the San Andreas fault system over the last 30 million years is shown below. The Pacific plate currently is moving past the North American plate at a rate of about 3.5 cm/year.

During what time (in millions of years) would you expect volcanoes near Los Angeles?

Why would there be volcanoes at this time (i.e., what would create them)?

Should the volcanoes be active today? Why or why not?

Using the scale on the map and the rate of plate motion above, determine how long it will take Los Angeles to reach San Francisco.

30 million years ago 20 million years ago 10 million years ago Present PACIFIC PLATE JUAN DE FUCA PLATE Trench EXPLANATION Trench San Francisco Spreading center (divergent boundary) PACIFIC PLATE PACIFIC PLATE PACIFIC PLATE Subduction zone Los Angeles PACIFIC PLATE (convergent boundary) Los Angeles Z Los Angeles Los Angeles Transform fault, arrows show relative movement SAFZ, San Andreas fault zone 1 RIVERA PLATE Triple plate junction Guif of O California M. Mendocino R. Rivera cocoS PLATE COCOS PLATE Trench Trench Trench Trench cocoS PLATE 200 km

Explanation / Answer

1) between 19-13million years volcanic rocks are found.

2)subduction takes place to cause of volcanoes formation.pacific plate movement toward the North American plate

3) the volcanoes active between 2.5-1.5 million years ago.

4)

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