Sea Floor Features The Topography of the Ocean Floors

Hypsographic Curve Distribution of elevations and depths on Earth Avg elevation= 2760 feet Avg. depth = 12,451 feet

The Misconception… Earth’s crust is one solid layer Like an M&M

Reality

The Misconception… The ocean is deepest in the middle Deepest Part

The Misconception… The ocean floors are flat and featureless

? How do we know what we know?

Bathymetry The discovery and the study of the ocean floor contours

Sounding, The Early Years Measured to a depth of almost 5 mi.

Improvements- Sound

Improvements- Satellites

Submersible Submarine or equipment used to go under water Ex: Alvin

What does the ocean floor look like?

2 Provinces or sections Continental Shelf Ocean Basin

Continental Margins Continent extends into ocean Granite Crust

Two Types Active Tectonically active West coast Passive Tectonically inactive East coast

Factors shaping land today? What shapes the coasts today? Waves Storms Wind Uniformitarianism Forces always present Catastrophism Catastrophies How could these factors have affected the continental crust underwater?

The Sea Is Not On The Level… Fluctuations of sea level exposed and covered land Continental shelf extends about 130 m below sea level Level of sea at last ice age = 130 m below present Coincidence?

The Anatomy

More on Sea Level Rock exposed at last ice age Cave formed Filled with water after sea level rise Attraction for divers

Deep Ocean Basins

Abyssal Plains Flat More in Atlantic Covered by sediments Up to 3,300 feet deep

Mid-Ocean Ridge

Formation of New Sea Floor

Hydrothermal vents or Black Smokers Near mid-ocean ridges Release heat and chemicals Emit Sulfides = Black Smokers

How did the Hawaiian islands form? Wish I was here!!!

Older islands move with tectonic plate Lava pushed up New land forms

Old Islands Maui Hawaii Oahu Still wish I was here!!! Hot Spot PLATE DIRECTION

Seamounts and Guyots That’s Ge-o

Trenches and Island Arcs Trench is a deep depression in the sea floor Occur at subduction zones Islands form adjacent

Music by IZ Iz Over the Rainbow: A Hawaiian Tribute Israel Kamakawiwo'ole