11_Ocean Floor

Ocean Floor Overview

  • Presenter: Dr. Jackie Miranda

  • Date: February 24, 2025

Agenda

  • 60-Second News Update: Muhammad and Autumn

  • Key Topics:

    • Ocean Basins

    • Continental Margins & Ocean Ridges

    • Seafloor Mapping

    • Ocean Sediments

    • Seafloor Lab

News Updates

  • Muhammad and Autumn: Updates related to ocean research and events.

Upcoming Events

Tampa Bay Youth Ocean Summit

  • Date: March 1

  • Time: 9 AM – 5 PM

  • Themes:

    • Wildlife over Waste

    • Save Florida’s Whales

    • Protect Coral in the Florida Keys National Marine Sanctuary

    • Climate Change and Our Ocean

Denis Phillips Guest Lecture

  • Date: March 26

  • Time: 7 PM – 8:45 PM

  • Location: Tarpon Springs Campus, Chris Sprowls Workforce Innovation Hub

  • Focus: Community service, social media, and weather

Quiz Questions Review

  • Quiz Question 1: Type of stream in the image?

    • Options: A. Braided stream, B. Low sinuosity stream, C. Steep terrain stream, D. Meandering stream

  • Quiz Question 2: What is the top horizon of soil called?

    • Answer options: A. True, B. False

Importance of Oceans

  • Climate: Contributes to global climate patterns

  • Resources: Energy extraction and transportation of goods

  • Recreational Use: Provides areas for recreation

Oceans Statistics

  • Earth's Surface: 71% is covered by oceans and marginal seas

  • Ocean Coverage:

    • Northern Hemisphere: 61% ocean

    • Southern Hemisphere: 80% ocean

Ocean Basins

  • Major Ocean Basins:

    • Pacific Ocean: Largest, deepest (average depth: 4,282 m)

    • Atlantic Ocean: Second largest, less depth (average depth: 3,926 m)

    • Arctic Ocean: Shallowest (average depth: 1,205 m)

    • Indian Ocean: Similar depth to Atlantic (average depth: 3,741 m)

    • Southern Ocean: Equivalent depth to Atlantic and Indian (average depth: 3,270 m)

Deep Ocean Exploration

  • Exploration Status: Only 5% of the world’s oceans have been explored; 26.1% of the ocean floor mapped as of June 2024.

Continental Margins and Ocean Ridges

  • Types of Margins:

    • Active Margins: Associated with tectonic plate boundaries, experience volcanism and earthquakes.

    • Passive Margins: Not associated with plate boundaries, experience little volcanism.

  • Continental Shelf: Shallow, flooded edge of the continent, often containing oil and mineral deposits.

  • Continental Slope: Steeper area leading from the shelf to deeper regions.

  • Continental Rise: Where continental slope becomes gradual and accumulates sediment.

Submarine Canyons and Turbidity Currents

  • Submarine Canyons: Deep, steep valleys on continental slopes, often formed by turbidity currents.

  • Turbidity Currents: Dense, sediment-laden water flows downslope, depositing turbidite layers characterized by graded bedding.

Active Continental Margins

  • Found mainly around the Pacific, featuring deep ocean trenches and significant volcanic activity.

Deep-Ocean Trenches

  • Long, narrow, and the deepest parts of oceans located primarily in the Pacific. Associated with volcanic activity and plate tectonics.

Abyssal Plain

  • Deep ocean floor covering depths from 4,500 to 6,000 m, characterized by thick sediment accumulations.

Seamounts and Guyots

  • Undersea volcanic peaks that can emerge as islands or erode to become flat-topped structures (guyots).

Oceanic Ridge System

  • Mid-Ocean Ridge: Longest topographic feature on Earth, characterized by extensive faulting and volcanic structures, spanning approximately 70,000 km.

Hydrothermal Vents

  • Critical for supporting unique ecosystems; formed near tectonic plate boundaries with geothermally heated water.

Review Questions

  • World's Oceans Coverage: About 71% of Earth.

  • Southern Hemisphere Ocean Coverage: True – more ocean coverage than Northern Hemisphere.

Seafloor Mapping Technology

  • Tools:

    • Echo sounders for depth measurement.

    • Sidescan sonar and multibeam sonar for detailed mapping.

    • Satellite altimeter for measuring the ocean surface shape from space.

Seafloor Sediments

  • Main types of sediments include:

    • Terrigenous: Weathered material from land.

    • Biogenous: Derived from marine organisms.

    • Hydrogenous: Minerals crystallized directly from seawater.

Climate Impact of Sediments

  • Provide a record of life and climatic conditions, essential for understanding Earth's climate history.

What Did You Learn Today?

  • Reflect on three key takeaways and the most confusing aspects of today’s class.