Lesson 1 Physical and Chemical Weathering

Jekyll Island Overview

  • Location: Off the coast of Georgia, Glynn County.

  • Ownership: Owned by the State of Georgia, self-governing body.

  • Attractions: Popular tourist destination with beaches, bike trails, Summer Waves water park.

  • Historic District: Features buildings from the late 19th and early 20th centuries.

  • Wildlife: Home to various mammals, reptiles, and birds in salt marshes.

Weathering

  • Definition: Breaking down or dissolving of rocks and minerals on Earth's surface.

  • Types:

    • Physical Weathering

    • Chemical Weathering

Physical Weathering

  • Involves mechanical breakdown without changing chemical composition.

  • Causes:

    • Wind

    • Water

  • Effects: Rocks become smaller, rounded, lose sharp edges. Can cause holes due to abrasion.

  • Unique Process: Freezing and thawing of water causes expansion, leading to rock fracturing.

Example of Physical Weathering

  • Scenario: Statues at a library rounded and less detailed due to weathering.

  • Cause: Likely weathering of the stone.

Chemical Weathering

  • Definition: Breakdown of rock through chemical reactions.

  • Examples:

    • Reaction with water (e.g., Alka Seltzer in water forming carbonic acid).

    • Iron rusting due to oxidation.

  • Significance: Forms new substances, important in cave and sinkhole formation.

Erosion and Deposition

  • Erosion: Movement/transportation of rock materials, caused by gravity or weather.

  • Deposition: Dropping off of eroded materials in new locations, forms features like river deltas.

  • Importance: Changes Earth's surface significantly over time; affects landforms like the Grand Canyon.

Groundwater and Aquifers

  • Definition: Fresh water in openings of soil and rock, crucial for drinking water supply.

  • Aquifers: Porous rock/soil formations that can store groundwater (e.g., limestone, gravel).

Acids in Weathering

  • Role of Acids: Acids formed during rock alteration or from rain dissolve minerals.

  • Common Acid: Carbonic acid through CO2 and water reaction.

  • Consequences: Vital in sinkhole formation.