physical geology quiz 1

What was the simple observation from Eratosthenes to interpret shape and size of planet?

On summer solstice, sun was directly above and shone down a well without a shadow. But in Alexandria at the same time, there was a shadow.

What is the Earth’s radius?

6370 km

What is Moho?

The boundary between the Earth’s crust and the mantle.

Lithosphere vs Asthenosphere?

Lithosphere is uppermost part of mantle and non-flowable. Asthenosphere is relatively soft and can flow.

Which 4 elements make up 90% of Earth?

Fe, Si, O, Mg

Which is the most abundant in Earth?

Fe

What is the most common element in the Earth’s CRUST?

O2

Which part of Earth is entirely liquid?

Outer core

What are two differences between P-waves and S-waves?

P waves are compressional waves that are faster and propagate through liquids and solids. S-waves only propagate through solids.

Describe S-wave shadow zone

S-waves cannot travel through liquid. There were no s-waves beyond 104 degrees, indicating there to be liquid within the Earth.

3 differences between oceanic and continental crust?

Oceanic: thinner 6-7 km, basalt composition, young (0-180 Ma)

Continental: thicker 25-70 km, granite composition, old (1-2 Ga)

Which part of the Earth’s internal structure produces its magnetic field?

The outer core

What part of the continent is called the “continental shelf”

Shallow seafloor on the edge of a continent.

What is the “continental slope?”

The steep drop down between the shelf and deep ocean.

5 observations of Alfred Wegener’s hypothesis of continental drift.

1. Edge of continents lined up like a puzzle

2. Same fossils were found on southern continents

3. The geology of coastlines matched different continents

4. Glacier deposits on each continent formed an ancient polar ice-cap

5. Paleomagnetism, evidence of tectonic plates moving

What is paleomagnetism?

The record of ancient magnetism preserved in rock.

What are magnetic reversals?

Evidence of reversed polarity of the Earth.

What are mid-oceanic ridge?

Long submarine mountain belts

What is sea floor spreading? List 3 observations.

Sea floor spreading is the gradual widening of an ocean basin

1. Hess observed the thinness of the sea floor

2. Seafloor crust was young

3. Mid-Ocean Ridges creating new oceanic crusts

What is apparent polar wander? How did they show the continents must have moved positions?

A path that shows a magnetic pole moved over time. But, in reality the continents were moving because they have different relative paths.