Test review

Geological Processes Review

1. Name the layers of the earth. Note which layers that make up the lithosphere and asthenosphere.

• Inner core

• Outer core

• Lower Mantle

• Upper Mantle

• Crust

2. Compare and contrast Oceanic and Continental crust

Oceanic crust is made of hardened mantle and sediments. Continental crust is made of hardened mantle that rises above the ocean to form land. Oceanic crust is denser and will subduct under continental crust in collisions.

3. Describe the 4 arguments Wegener used to support his theory of continental drift

•  Puzzle pieces (continents appear to fit together ex. South america and africa)

•  Fossils (species such as the Glossopteris plant found across multiple continents)

•  Climate inconsistencies (coal is formed in hot climates, but it is found in antarctica, Glacial evidence in africa and other hot places)

•  Geological structures (mountain ranges that line up, rocks of the same type and âge on multiple continents)

4. Describe 3 ways scientists are able to identify the composition of the Earth’s interior

•  Seismic waves ( s-waves cannot travel through liquids, so there are shadow zones. We detect bends in how the waves travel as they go through different densities)

•  Meteorites (made of the same material as early earth)

•  Overall density of the earth (it is denser that just the crust rock, therefore there must be a solid core)

• Magnetic field (presence of a magnetic field indicates metal core Fe and Ni)

5. Describe 3 steps for how new oceanic crust is formed.

•  Oceanic plates diverge

•  Hot mantle rises up from the crack

•  Ocean water cools and hardens the magma to form new oceanic crust and a mid-ocean ridge

6. Fill in the table for the different types of plate boundaries

7. Fill in the table for the processes that cause plate movement

8. Fill in the table for the causes of plate growth

9. Briefly describe how each of these terms relates to the geological sequencing of rock layers. For each term, describe how one layer in the cross-section relates to it.

• Law of Superposition: In any sequence of rock layers, either unreformed sedimentary rocks or surface deposited igneous rocks, the youngest rocks are always at the top and the oldest at the bottom.

• Faulting: The process by which the Earth's crust breaks and shifts along fractures called faults. A fault is essentially a crack or zone of weakness in the Earth's lithosphere where two blocks of rock move relative to each other. Faulting occurs due to tectonic forces (such as compression, tension, or shear) that cause stress in the Earth's crust.

• Igneous Intrusions/contact metamorphism:

An igneous intrusion occurs when molten rock (magma) from deep within the Earth pushes its way into pre-existing rock formations (called the country rock or host rock) but doesn't reach the Earth's surface. As the magma cools and solidifies beneath the surface, it forms an intrusive igneous rock.

Contact metamorphism occurs when igneous intrusions (such as a pluton or sill) heat the surrounding rock (country rock) and cause changes in its mineralogy and structure due to the high temperature, without the rock undergoing melting. This process happens near the contact zone between the intrusion and the host rock. Unlike regional metamorphism, which occurs over large areas under high pressure and temperature, contact metamorphism is mainly driven by the heat from the intrusion.

10. Compare the different types of waves present during an earthquake:

The P waves travel faster and shake the ground where you are first. Then the S waves follow and shake the ground also. If you are close to the earthquake, the P and S wave will come one right after the other, but if you are far away, there will be more time between the two.

11. Describe the following terms:

• Epicentre: The location on the surface of the Earth directly above where the earthquake starts

• Focus: The location in the Earth where the earthquake starts

• Richter scale: Calculates an earthquake's magnitude (size) from the amplitude of the earthquake's largest seismic wave recorded by a seismograph

12. List some locations along the Pacific Ring of Fire. Compare this with a map of plate boundaries.

Japan, Indonesia, Philippines, New Zealand, Alaska (USA), Chile, Mexico, Peru, California (USA), Costa Rica, Nicaragua, Ecuador, Papua New Guinea, Antarctica

13. Compare and contrast the types of Volcanoes

Shield Volcanoes

• Because of its low viscosity, basaltic lava tends to flow long distances before hardening.

• In some cases, the lava builds up in layers, forming shield volcanoes with broad bases and gently sloping sides. 

• The broad base of a shield volcano can support a mountain of enormous height. For example, Mauna Loa, a volcano on the island of Hawaii, rises 4170 meters above sea level and its base is 5000 meters below sea level; thus, its total height is 9170 meters.

• Because shield volcanoes discharge basaltic lavas, they tend to be less explosive than other types of volcanoes. 

• Basaltic lava flows, however,may be frequent and copious, causing damage to homes, highways, and other property.

Cinder Cones

• Simplest type of volcano

• Smaller than other volcanoes

• Form in groups on the sides of other volcanoes

• Forms when molten lava is thrown into the air from a vent

• Fragments break apart and then harden before hitting the ground

• Fragments accumulate into a cone shaped mound with an oval base

Composite Volcanoes

• Composite volcanoes develop when layers of materials from successive explosive eruptions accumulate around a vent. 

• The materials include hardened lava flows and other pyroclastic material.

• Magma, water, and gases exploded in a massive cloud of superheated ash and stones. Some of the hot ash mixed with the snow and ice on the mountain to form a fast-moving mudflow called a lahar 

• In some areas, the debris from the lahar and landslides reached a depth of about 46 meters.

• After a violent eruption, a composite volcano may remain relatively quiet for a long period of time. 

• Beneath the surface, however, gas-rich magma may again be building up pressure, eventually leading to another explosive eruption.

Calderas

• Formed from magma the top of a volcano collapses into a crater shaped basin

• Sometimes found at the top of active volcanoes

• Can be filled with water to form a lake

• Heat from volcano can heat hot springs and geysers

Lava Plateaus

• Sometimes plate tectonics results in the formation of a long, narrow crack or fissure in Earth’s surface. 

• Basaltic lava pouring from the fissure spreads across the land, forming a lava plateau.

• The basaltic lava that formed the Columbia Plateau in the northwestern United States is over one kilometer thick in some places and covers an area of about 164,000 square kilometers.

14. Define weathering and erosion. List some methods of erosion.

Weathering is the process of decomposing, breaking up, or changing the color of rocks. Weathering may be caused by the action of water, air, chemicals, plants, or animals. Chemical weathering involves chemical changes in the minerals of the rock, or on the surface of the rock, that make the rock change its shape or color. Carbon dioxide, oxygen, water, and acids may all cause chemical weathering. Mechanical weathering is the process of breaking a large rock into smaller pieces without changing the minerals in the rock. Mechanical weathering may be caused by frost, ice, plant roots, running water, or heat from the sun.

Once the small pieces of rocks are changed or broken apart by weathering, they may start to be moved by wind, water, or ice. When the smaller rock pieces (now pebbles, sand or soil) are moved by these natural forces, it is called erosion.

So, if a rock is changed or broken but stays where it is, it is called weathering. If the pieces of weathered rock are moved away, it is called erosion.

15. Compare and contrast Dikes, Sills, and Batholiths

Batholiths form by multiple intrusions in the same region. Sheet-like intrusions include sills and dikes. Sills form parallel to layering in country rocks, dikes cut across layering. Dikes and sills range from silicic to mafic compositions, but most are mafic.

16. List 3 pieces of evidence left behind by glaciers

 As glaciers grind over the surface bedrock, they leave behind deep scratches in the rock.  These groves are called glacial striations

When a glacier melts, it deposits piles of and sediments. These sediments are known as glacial till. 

 A drumlin is an elongated hill of deposited glacial till. The shape of a  drumlin reveals the direction that the glacier was moving.  

Glaciers grind down the rock on both the sides and bottom of the area where they are  traveling. The result is a large, wide, u-shaped valley.