Earth's Surface and Geological Features

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Questions and Answers

Which type of seismic wave is also known as a compressional wave?

Love wave

R wave

S wave

P wave (correct)

During which geologic era do we currently live?

Precambrian

Paleozoic

Mesozoic

Cenozoic (correct)

Which feature represents the edge of the continental crust?

Oceanic trench

Continental slope (correct)

Continental shelf

Mid-oceanic ridge

What is the primary cause of earthquakes?

Movement of rock along faults Signup and view all the answers

What do we call the point on the Earth's surface that is directly above the focus of an earthquake?

Epicenter Signup and view all the answers

What percentage of the Earth's surface is occupied by oceans?

71% Signup and view all the answers

What are mountain roots?

Deep, stable portions of the Earth's crust supporting mountain ranges Signup and view all the answers

What is the primary concept explained by the elastic rebound theory?

The storage and release of energy in fault lines Signup and view all the answers

What is formed when divergent boundaries occur?

Rift valleys Signup and view all the answers

Which process transforms existing rocks into metamorphic rocks?

Metamorphism Signup and view all the answers

What type of rock is characterized by high silica content?

Felsic rocks Signup and view all the answers

What occurs at convergent boundaries?

Plates slide towards each other Signup and view all the answers

Which is NOT a feature associated with convergent boundaries?

Rift valleys Signup and view all the answers

How many major lithospheric plates does the Earth's lithosphere have?

Six Signup and view all the answers

What is the main component of rocks?

Minerals Signup and view all the answers

Who proposed the theory of continental drift?

Alfred Wegener Signup and view all the answers

Which feature differentiates oceanic crust from continental crust?

Oceanic crust is denser and thicker than continental crust. Signup and view all the answers

What type of rock is formed from the solidification of molten magma or lava?

Igneous rocks Signup and view all the answers

What is the primary composition of the outer core of the Earth?

Iron and nickel Signup and view all the answers

How does the lithosphere move in relation to the asthenosphere?

The lithosphere moves on top of the semi-fluid asthenosphere. Signup and view all the answers

What characteristic allows the asthenosphere to facilitate tectonic plate movement?

It is partially molten, allowing flow. Signup and view all the answers

What occurs at the boundaries of tectonic plates?

Earthquakes and volcanic activity. Signup and view all the answers

Which type of igneous rock forms from magma that crystallizes slowly beneath the Earth's surface?

Intrusive Signup and view all the answers

What is the role of the inner core in relation to the Earth's structure?

It is a solid sphere under immense pressure. Signup and view all the answers

Study Notes

Earth’s Surface Composition

29% of Earth’s surface is land and 71% is ocean.
Continental shelf area increases the land area to 35% and decreases the ocean basin area to 65%.

Oceanic Relief Features

Mid-oceanic ridge with a central rift where crust is pulled apart.
Continental shelves accumulate thick deposits of continental sediments.
Continental slopes are the edge of the continental crust.
Oceanic trenches are where oceanic crust slides beneath continental crust.

Continents

Divided into active mountain-making belts and inactive regions of old, stable rock.
Continental shields and mountain roots are two types of stable structures.
Mountain Roots are the deep, stable portions of the Earth's crust that support mountain ranges.

Time Scale

Time older than 570 million years (MY) is Precambrian time.
Three eras of time follow: Paleozoic, Mesozoic, and Cenozoic.
Geologic eras are subdivided into periods.
We live in the Holocene period (the last 12,000 years).

Earthquakes

Shaking and trembling caused by rock movement beneath Earth's surface.
Most severe earthquakes occur near plate collision boundaries.
Earthquakes are the sudden release of stored energy.
Result of fast movement between two blocks of rock.
Released energy radiates away from the earthquake.
Main cause of earthquakes is faults on the Earth's crust.
A fault is a break between two blocks of rocks.

Earthquake Terminology

The origin of the earthquake (where the fault begins) is the focus or hypocenter.
The point on the Earth's surface directly above the focus is the epicenter.

Elastic Rebound Theory

Explains how energy is stored in deformed rocks along fault lines and released during an earthquake.
Seismic waves are vibrations that travel through Earth carrying energy released during an earthquake.

Seismic Waves

Two types of waves produced during an earthquake.
Body waves: travel through Earth’s interior.
- P wave (primary): compressional wave that causes alternate compression and expansion of the rock.
Surface waves: travel along the Earth’s surface.

Metamorphic Rocks

Created when existing rocks are transformed by heat, pressure, or chemically active fluids.
This process, known as metamorphism, changes the mineral composition and structure.

Earth's Composition

91 elements occur naturally in the Earth’s crust.
Eight elements make up more than 98 percent of the earth’s crust.
A mineral is a naturally occurring, inorganic solid with a characteristic chemical composition and a crystalline structure.
Felsic rocks (comprising the crust) are high in silica content.
**Ultramafic rocks **(comprising the mantle) are high in magnesium and iron content.

Plate Tectonics

The theory proposed by Alfred Wegner in 1912 suggests that the crustal plates are moving over the mantle.
Wegner proposed that today’s continents once formed a single landmass, called Pangaea.
The uppermost mantle and the overlying crust behave as a strong, rigid layer, known as the lithosphere, which is broken into segments called plates.

Lithospheric Plates

The Earth’s lithospheric shell is divided into six great lithospheric plates and at least nine lesser plates.
Divergent boundaries (Constructive): two plates slide apart from each other. They are characterized by:
- Rift valleys
- Tilted block mountains
Convergent boundaries (Destructive): two plates slide towards each other, forming either a subduction zone or a continental collision. They are characterized by:
- Trenches
- Mountain ranges
- Island arcs
- Volcanic arcs
Transform boundaries (Conservative): plates slide past each other along transform faults.

Earth Structure and Composition

The layers of the Earth’s interior include the crust, mantle, liquid outer core, and solid inner core.
Crust: outermost layer, thinnest and solid, composed of continental and oceanic crust.
Mantle: thick layer beneath the crust, semi-solid rock that flows slowly.
Outer Core: Liquid layer beneath the mantle, composed mainly of iron and nickel.
Inner Core: innermost layer, solid sphere due to high pressure, primarily iron and nickel.

Lithosphere and Asthenosphere

Lithosphere: rigid outer layer of Earth (crust + upper mantle).
Asthenosphere: semi-fluid layer of the upper mantle beneath the lithosphere.

Rocks

Rocks are aggregates of mineral particles.
Igneous Rocks: formed from the solidification of molten magma or lava.
- Intrusive (Plutonic): crystallize slowly beneath the Earth's surface.
- Extrusive (Volcanic): erupt and cool quickly on the surface.
Sedimentary Rocks: formed from the accumulation and compaction of sediments.

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Description

Explore the composition of Earth's surface and the various geological features found within our oceans and continents. This quiz covers land-to-ocean ratios, oceanic relief features, and the geological timescale, including major eras and periods. Test your knowledge about the Earth's structure and its history!