Geological Features: Folds and Faults

Geological Features: Folds

• Folds are rock layers compressed by stress.
• Three main linear fold types:
  • Anticlines: arched, older rocks at center.
  • Synclines: concave up, older rocks on the outside.
  • Monoclines: one prominent dipping slope.
• If rock age is unknown or reversed, use antiforms/synforms instead of anticlines/synclines.
• Further fold classifications: asymmetric, symmetric, overturned, recumbent, isoclinal, Chevron, parasitic, ptygmatic, disharmonic.
• Domes and basins formed by connecting anticlines/synclines.
• Plunging anticlines/synclines have tilted hinge lines.
• Folds identified by tightness, axial plane orientation, and bed thickness.

Plate Tectonics and Faults

• Earth's crust composed of tectonic plates.
• Plate boundaries where plates meet.
• Faults are fractures in the crust along plate boundaries.
• Two sides of a fault:
  • Hanging wall: above the fault.
  • Footwall: below the fault.
• Normal faults: hanging wall moves down.
• Reverse faults: hanging wall moves up.
• Three types of stress causing faults:
  • Compressional: pushes blocks together (reverse).
  • Shear: blocks slide past (strike-slip).
  • Tensional: pulls blocks apart (normal).

Mountain Formation (Orogeny)

• Mountains are high-altitude geologic features.
• Made of rock formed from minerals.
• Fold mountains form from colliding continental plates.
• Dome mountains form from magma rising and cooling.
• Subduction (one plate sinking under another) creates mountain ranges.
• Hotspot mountains form from magma rising at fixed points (e.g., Hawaii).
• About 40-50 global hotspot locations. Not all islands are hotspot mountains.
• Oceanic plate collisions can also create mountains.

The Water Cycle

• Recycles freshwater on Earth.
• Main parts: evaporation, condensation, precipitation.
• Water changes phases (liquid, solid, gas).
• Processes in order: evaporation, condensation, precipitation, sublimation, transpiration, runoff, infiltration.
• Water enters atmosphere through evaporation, sublimation, transpiration.
• Condensation forms clouds, leading to precipitation (rain, snow, sleet, hail).
• Runoff carries water to rivers and eventually groundwater.

Water Distribution and Importance

• 97% of Earth's water is salty.
• Only 3% is freshwater, mostly locked in glaciers/ice.
• 30% of freshwater is underground, very important to humans.
• Less than 1% of the world's water is readily available (surface).
• Still a vast amount of freshwater is available, however, the accessible amount is limited.

Water Cycle Processes: Evapotranspiration, Condensation, Precipitation

• Water cycles around the planet.
• Evapotranspiration: evaporation from surfaces + transpiration from plants.
• Evaporation rates increase with sunlight, dryness, wind, heat.
• Transpiration occurs through plant stomata.
• Water condenses into clouds.
• Precipitation (rain, snow, sleet) returns water to the surface.

Runoff and Infiltration

• Runoff: water flowing across the land surface.
• Infiltration: water seeping into the soil.
• Runoff occurs on non-porous surfaces or saturated ground.
• Runoff collects in ravines, gullies, etc., heading to larger water bodies.
• Runoff can erode land, harming ecosystems.
• Infiltration rate depends on soil permeability, slope, and vegetation.

Drainage Basins and River Systems

• Drainage basin (watershed): area where water drains into a common outlet (river).
• Drainage basins vary in size.
• Drainage divides (high ground) separate basins.
• River systems begin as small streams (first-order), merge into larger streams.

Streamflow: Laminar and Turbulent

• Streamflow: water movement in a stream channel.
• Laminar flow: smooth, parallel layers, slow velocity.
• Turbulent flow: random flow, fast velocity due to obstacles.

Explore the fascinating world of geological folds and faults. This quiz covers the definitions, classifications, and characteristics of various fold types and their relationship with plate tectonics. Test your knowledge on structures like anticlines, synclines, and the mechanics of faults.