GEOG LAB Exam #2

Divergent plate boundaries

are areas where two plates are pulling apart and new crustal material is being created

convergent plate boundaries

areas where two plates are coming together or colliding;

examples of convergent plate boundaries

mountain ranges and deep ocean trenches

Oceanic-Continental Convergent Plate Boundaries

• denser and thinner than continental crust, so it sinks into the mantle when they collide.

• Key Features:

  • Subduction zones and deep ocean trenches (e.g., Peru-Chile Trench).

  • Volcanic mountain ranges on the continental plate (e.g., the Andes Mountains).

  • Earthquakes caused by the subduction process.

Oceanic-Oceanic Convergent Plate Boundaries

• When two oceanic plates meet, the older plate (denser due to cooling) is forced beneath the younger one, forming a subduction zone.

• Key Features:

  • Deep ocean trenches (e.g., Mariana Trench).

  • Volcanic island arcs (e.g., the Aleutian Islands in Alaska or the Philippines).

  • Intense seismic activity and underwater volcanoes.

• 
  

Continental-Continental Convergent Plate Boundaries

Formed when two continental plates collide, leading to the uplift of mountain ranges and the creation of large mountain systems. This type of boundary is characterized by a lack of subduction and intense geological activity.

Which plate boundary (convergent, divergent, transform) contains the most geologic hazards? Which hazards occur here?

Convergent plate boundaries contain the most geologic hazards, including earthquakes, volcanic eruptions, and tsunamis due to the intense interactions between colliding plates.

Why doesn’t Australia (the country, not the plate) have any active volcanoes?

Australia is located in the middle of the Indo-Australian Plate, far from tectonic plate boundaries where volcanic activity typically occurs.

identify the type of plate boundary present: 

Central America, between the Caribbean and Cocos plates

This is a convergent plate boundary, where the Cocos Plate is being subducted under the Caribbean Plate, often resulting in volcanic activity and earthquakes.

identify the type of plate boundary present:

The Red Sea, between the African and Arabian plates 

This is a divergent plate boundary, where the African and Arabian plates are moving apart, leading to the formation of new oceanic crust and potential volcanic activity.

identify the type of plate boundary present: 

The Himalaya, between the Indian and Eurasian plates

This is a convergent plate boundary, where the Indian Plate is colliding with the Eurasian Plate, resulting in the uplift of the Himalayas and frequent seismic activity.

identify the type of plate boundary present: 

California, between the North American and Pacific plates

This is a transform plate boundary, where the North American and Pacific plates slide past each other, often causing earthquakes.

What are effusive volcanic eruptions?

where the magma has a much lower proportion of silica thus a lower viscosity allowing it to flow easily and produce relatively gentle eruptions, often resulting in the formation of lava flows rather than explosive activity.

What are explosive volcanic eruptions?

4 characterized by a high silica content in the magma, resulting in higher viscosity. This leads to the buildup of pressure and violent eruptions, producing ash clouds and pyroclastic flows.

cinder cone

the result of an explosive eruption, but is comprised primarily of cinder-sized tephra.

Why are effusive eruptions not as explosive? What type of cone or other features may be formed because of effusive eruptions?

Effusive eruptions are not as explosive because there is less viscosity of silica in the magma, and not as much gas pressure built up. Shield volcanoes form after effusive eruptions. They also produce a volcanic cone with broad, gentle slopes, composed of layer upon layer of fluid basalt lava. 

 

Describe the difference between volcanoes which form in places like Hawaii (Mauna Loa, etc.) versus those that form the Cascade Range (Mt. Rainier, etc.) in the U.S. (Type of cone, location relative to tectonic plates, type of eruption, etc.)

 

Volcanoes in places like Hawaii typically form hotspot activity. They usually have shield volcanoes and effusive eruptions. These eruptions are usually effusive explosions. Volcanoes that form in the Cascade Range are usually stratovolcanoes. Eruptions here are normally explosive eruptions. 

intrusive volcanic features

If magma cools within the crust

extrusive volcanic features

features formed from the cooling of lava on the surfac

Shield Volcanoes

• Description:
  Broad, gently sloping cones made primarily of low-viscosity basaltic lava.

• Key Features:

  • Large base with a dome-like profile.

  • Built by successive, fluid lava flows.

  • Often associated with hotspot volcanism (e.g., Hawaiian Islands like Mauna Loa).

• Eruption Style:
  Effusive eruptions with lava flowing over long distances.

Stratovolcanoes

• Description:
  Tall, symmetrical cones built from alternating layers of lava flows, volcanic ash, and other pyroclastic materials.

• Key Features:

  • Classic "volcano" shape with steep upper slopes and gentler lower slopes.

  • Commonly associated with subduction zones (e.g., Mount Fuji, Mount St. Helens).

  • Capable of producing devastating eruptions.

• Eruption Style:
  Mixed; both explosive (pyroclastic) and effusive (lava flows).

what type of eruption is this

effusive

composite

cinder cone

cinder cone

shield volcano

collapsed caldera

batholith

batholith stone mountain

volcanic neck

Hydraulic action

is the work of the moving water itself, the turbulence caused by the flowing action of the stream

Abrasion

the process of a stream using the materials carried by the water to hit and dislodge other materials along the sides or bottom of the watercourse. 

Corrosion

the process whereby materials dissolve into the water.

downcutting

making the watercourse deeper

lateral erosion

making the watercourse wider

headward erosion

making the stream longer

hydraulic action and abrasion

lateral erosion

headward erosion

Left-Point Bar Right-Meander

delta

youth stage v shaped

mature stage

old age stage

Kettles

are formed when large blocks of the ice break-off from the glacier and sink into ground moraine as the ice sheet melts

kettle lakes

The eventual melting of these blocks forms depressions that may fill with water to form

kames

are round mounds of glacial drift left after the ice retreats.

drumlins

are elliptical shaped mounds formed as the ice retreats which can indicate the direction of glacier flow, which is parallel to the long axis of the drumlin in the direction of its tail

Meltwater streams

flowing beneath a glacier may form an ice tunnel, produced when the “warm” stream waters melt the ice.

esker

These tunnels may eventually fill up with sand and gravel and when the ice retreats, these deposits are left as sinuous ridge called an

Pluvial Lakes or Paleolakes

refers to lakes that existed during a past Ice Age,

Describe the formation of the Great Lakes in North America and how these are different from paleolakes.

The Great Lakes formed during the Ice Age when the land was covered by ice sheets that later melted and receded towards the south. The glacial erosion formed basins and valleys where the Great Lakes later emerged. These form in depressions scoured out deeper, wider, and longer by continental ice sheets. Paleolakes refers to lakes that existed during the past Ice Age, but do not exist today or are smaller today than in the past. 

alpine glacier

crevasses

abrasion

glacial valley

hanging valley

fjord

kames

kettle lakes

sandspit

barrier island

tombolo

sea cliffs

sea stacks

what are the 4 soil components? M.O.W.A

Minerals, organic material, water, air

What are the soil formation factors?

parent material, climate, biological agents, topography, and time.

Field Capacity

the ability of a soil to hold water against the downward pull of gravity.

the largest capacity

sand

the smallest capacity

clay

List the four soil forming processes in soil formation

The four primary soil forming processes are addition, transformation, depletion, and translocation

O horizon

addition

E horizon

Depletion

A horizon

transformation and addition

B horizon

Translocation

C horizon

Transformation

The four components of waves

Wave height, wave frequency, wavelength, wave period

What causes wave refraction and how does this redirect energy along a coastline?

Wave refraction is caused by waves moving from deeper to shallower water at an angle at the coastline resulting in an uneven distribution of wave energy along the coast, concentrating it on some areas and minimizing it on others. Wave refraction redirect energy laterally along the shore forming currents. 

blue

wave refraction

. Describe how longshore currents form and what is established as a result of these currents

Longshore currents are formed because of waves approaching the shore at an angle instead of parallel. Longshore or beach drift are established as a result of longshore currents. 

The protrusion of land

Headland

rock mass

sea stack

flat area

wave cut platforms