Exam 2: Geography

Solifluction

A specific type of creep occurring in high-latitude and high-elevation tundra landscapes, where the thawing of the active layer during summer causes surface material to sag and move downslope.

Landslide

A type of mass wasting event involving the rapid and often catastrophic downhill movement of large masses of rock and soil, sometimes triggered by factors like rainfall or earthquakes.

Slump

A type of slide where materials move downward and outward along a curved sliding plane, creating a distinctive scarp at the top and a bulging lobe at the bottom.

Talus Slopes (Cones):

Accumulations of unsorted rock fragments at the base of steep slopes, forming cone-shaped heaps due to the falling of rocks and gravity.

What can get inside the rock through these openings?

Agents of weathering such as water, air, and plant roots.

Exfoliation

Also known as "sheeting," exfoliation results from pressure release as overlying materials erode, causing outer layers of rocks to peel away. This process is common in granitic rocks.

terraces (depositional or erosional)

BOTH

base level

Base level refers to the lowest point to which a stream can erode its channel. It can be categorized into two types:Ultimate Base Level: This is the lowest point a stream can erode, which is typically sea level. The ocean serves as the ultimate base level for most streams as it represents the lowest point of downcutting.Temporary Base Level: These are local or temporary limits imposed on streams by structural or drainage conditions. For example, lakes, resistant bedrock layers, or confluences with other streams can act as temporary base levels. Streams cannot erode below these local base levels.

What are faults?

Breaks in bedrock with relative displacement of walls.

What causes the formation of joints in lithospheric bedrock?

Contraction of molten material, sedimentary strata, and tectonic stresses.

What can cause the contraction of molten material?

Cooling.

What are joints?

Cracks in rocks without displacement along the breaks.

What can a well-developed joint system do to sedimentary rock?

Divide it into a regular series of close-fitting blocks.

What are the openings in rocks like?

Doors for agents of weathering.

What can cause the contraction of sedimentary strata?

Drying.

processes In arid environments

FLUVIAL (rivers) AEOLIAN ( wind) DIFFERENTIAL

Are jointing patterns more regular in fine-grained or coarse-grained rocks?

Fine-grained rocks.

Are the resulting blocks more sharply defined in fine-grained or coarse-grained rocks?

Fine-grained rocks.

Graded Stream Processes:

Graded streams represent a theoretical equilibrium where the amount of sediment entering a stream section equals the amount leaving it. This condition ensures that the stream's gradient and sediment-carrying capacity are balanced. Graded streams aim to transport sediment efficiently without excessive erosion or deposition. The stream's profile may be smooth, stepped, or a combination of both, depending on various factors, but the long-term tendency is to attain a graded profile. Achieving a graded profile helps maintain stream stability and minimizes excessive erosion or sediment deposition.

HYDROTHERMAL FEATURES

HOT SPRINGS GEYSERS FUMAROLES

What are solution cavities?

Holes formed in carbonate rocks due to dissolution.

What are lava vesicles?

Holes in cooling lava due to trapped gas.

Stalactite:

Icicle-like formations that hang from cave ceilings, formed by dripping water containing dissolved minerals CIELING ICICLES

Flows (Earth, Mud)

Mass movements involving the flow of material. Earthflows are slow-moving and often occur after heavy rainfall, while mudflows are more rapid and often carry a higher water content, particularly in arid regions.

What is the visible separation between blocks on either side of a joint?

Minimal below the surface.

four drainage basins

Mississipi, Columbia Colorado St. Lawrence

Mechanical Weathering:

More common in cold climates with freeze-thaw cycles, arid regions with extreme temperature changes, and coastal environments with salt spray. Mechanical weathering processes are driven by physical forces such as temperature fluctuations and salt crystallization.

What is weathering?

Natural aging process for rocks.

Joints

Natural fractures or cracks that occur in rocks due to various geological processes, providing pathways for weathering agents to act upon.

Frost Wedging:

Occurs when water enters cracks in rocks, freezes, and expands, exerting pressure that fractures the rocks. This process is particularly effective in regions with freeze-thaw cycles.

What are the openings or spaces that develop in rocks during weathering called?

Pores or openings.

Master Joints

Prominent and often large joints within rock masses that significantly influence the overall structure and susceptibility to mechanical weathering.

Dissolution

Rainfall and humidity promote this process, eroding rock and creating voids. Fractures in the rock aid water penetration. This dissolution forms distinct karst landforms like sinkholes, altered drainage, and underground networks.

Temperature Change:

Rocks expand and contract as they are repeatedly heated and cooled due to daily or seasonal temperature variations. This leads to the development of cracks.

Sinkholes

Rounded depressions formed by the dissolution of carbonate rocks, often at joint intersections.

Salt Wedging:

Salt crystals grow within rock cracks, applying pressure as they expand, ultimately leading to the fracturing of the rocks. Salt wedging is often found in coastal areas due to salt spray.

What are joint sets?

Series of approximately parallel fractures.

What are microscopic openings?

Spaces between crystals or grains in rocks.

What do rock openings serve as?

Starting points for the weathering process.

Towers

Steep-sided hills or conical landforms, particularly found in areas of karst topography like southeastern China and western Cuba. BIG HILLS WITH LINES ON THE SIDES

stream competence

Stream competence measures the maximum size of sediment particles a stream can transport and is primarily controlled by the stream's velocity (flow speed).

Stalagmite

Structures that grow upward from cave floors, created by mineral deposits from dripping water. FLOOR ICICLES (but not ice its sediment)

In the context of the Colorado Plateau and the Grand Canyon:

Tectonic Uplift: The Colorado Plateau experienced tectonic uplift, which raised the land. As the land uplifted, the Colorado River and its tributaries had to adjust to this new landscape. Downcutting: Rejuvenation triggered the downcutting of the Colorado River and its tributaries, allowing them to incise deeper into the landscape. Formation of Entrenched Meanders: As the river downcut, it began to form entrenched meanders. These are deep, tightly curved river bends that result from the rapid downcutting and the river's effort to maintain its course in response to the uplifted landscape. Grand Canyon: The formation of entrenched meanders played a significant role in shaping the Grand Canyon. Over millions of years, the Colorado River deeply carved into the Colorado Plateau, creating the iconic landscape of the Grand Canyon.

What is weathering considered as?

The first step in making rocks get old and fall apart.

Angle of Repose:

The maximum angle at which a slope remains stable, preventing the movement of materials due to gravity. It is typically around 35-40 degrees, depending on material properties.

Weathering

The natural process of breaking down rocks into smaller particles or altering their chemical composition. It includes mechanical and chemical weathering. This is when rocks break down into smaller pieces because of things like weather, such as rain and wind, as well as living things.

Mass Wasting

The process in which weathered materials, such as rock and soil, move downslope under the influence of gravity. Mass wasting results from the weakening of the Earth's surface by weathering processes. This is when bits of rock move downhill over short distances because of gravity. It's like rocks and soil sliding down a hill.

Erosion:

The process of transporting weathered material from one location to another by natural agents such as wind, water, or ice. Erosion is responsible for shaping landscapes. This involves the removal, carrying, and dropping of pieces of rock over larger areas and sometimes much farther than what happens in mass wasting. It's like rocks getting picked up and moved by things like rivers or glaciers.

Creep

The slowest and least perceptible form of mass wasting, characterized by very gradual downhill movement of soil and regolith, often unnoticed due to its slow nature.

What do the agents of weathering spread their effects into?

The solid part of the rock.

Fall

The sudden and rapid downward movement of rock fragments, often triggered by factors like weathering, particularly common in mountainous regions.

What do these agents do once they get inside the rock?

They start breaking the rock apart.

What happens to rocks during weathering?

They start to break down.

Chemical Weathering:

Typically more effective in warm and humid climates with abundant water and vegetation. The presence of water and organic acids accelerates chemical reactions that alter rock composition.

valley deepening

Valley deepening involves the erosion of the streambed and leads to deeper, V-shaped valleys.

Valley widening

Valley widening involves the erosion of the valley's sides and leads to wider valleys and the formation of floodplains.

Why are joints more conspicuous at Earth's surface?

Weathering emphasizes the fractures.

What is a joint system?

When two prominent joint sets intersect at right angles.

Are joints common in most rocks?

Yes, joints are relatively common in most rocks.

fluvial processes in arid environments

alluvial fans salt flats lake formation and erosion

Stream capacity

capacity is a measure of the stream's potential to transport sediment and is directly related to its water volume and velocity. Increased rainfall, melting snow, or watershed area can contribute to higher stream capacity, as they lead to greater stream discharge.

floodplain (depositional or erosional)

depositional

natural levees(depositional or erosional)

depositional

oxbow lakes (depositional or erosional)

depositional

point bars (depositional or erosional)

depositional

Tufa

deposits resulting from hot spring water containing calcium carbonate. LOOKS LIKE SAND CASTLES BY WATER (HOT SPRINGS)

bluffs (depositional or erosional)

erosional

cutbank (depositional or erosional)

erosional

meander scars (depositional or erosional)

erosional

Salt flats

fluvial process rainwater flows over salt soil , leaves salt deposit on floor beehive shapes on floor

Rejuvenation is a

geological process that involves the renewed downcutting and erosion of a river or stream, typically caused by changes in tectonic uplift or a drop in base level. It results in the formation of entrenched meanders, which are deep, tightly curved river bends.

These external processes, which include:

gravity, water, wind, and ice, may seem small and ordinary, but their combined effects are incredible.

alluvial fans

high-intensity rainfall in the surrounding mountain ranges leads to the rapid erosion and transportation of sediment down into the valley When the water carrying sediment enters the valley, it slows down, depositing the sediment in a fan-shaped pattern.

HOT SPRINGS

hot water flows to surface COMING FROM UNDERFROUND dissolved mineral matter results in cones or terraces

Weathering below the surface can take place

in bedrock containing many openings such as joints (a) before weathering; (b) after weathering.

downcutting (fluvial processes)

is a fluvial process in which a stream or river primarily erodes and deepens its channel vertically, leading to the excavation and development of a deeper valley.

lateral migration (fluvial processes)

is a fluvial process where a stream or river primarily shifts or moves horizontally within its valley, altering its position within the landscape.

Denudation

is the process of wearing down and removing rock material from the Earth's surface. It happens through three main activities: weathering, mass wasting and erosion.

Internal processes

like plate movements and volcanic activity shape the Earth's features over long periods

rock opening (five are common)

microscopic opening joints faults lava vesicles solution cavities

precipitation

occurs when minerals dissolve in hot underground water and then solidify as the water cools upon reaching the surface. These deposits, primarily calcium carbonate, can form mounds and terraces. The solubility of minerals depends on temperature, with hot water holding more minerals

perennial, ephemeral and intermittent

permanent, seasonal, only after rain

signs of STREAM erosion

rounded material- means salt edges of rocks have been smoothed away from the force of water

what does alluvial mean

sediment deposited by stream

fumalores

surface cracks or vents IN HEAT SOURCES. CLOUDS OF STEAM 9hissing sound)

if the internal processes of landscape formation are overwhelming,

the external processes are inexorable

GEYSERS

type of hot springs but intermitted eruptions of hot water and steam. inactivity long until next one

External processes

work continuously to wear down and reshape the land.