Geology of the Oceans

Did we always have oceans?_____• Have they changed ?___________• Oceans formed between 4.2-3.8 billion years ago– Water vapor escaping from crust condensed on

surface– http://www.youtube.com/watch?v=hwVU0-2Qnso&safety_mode=true&persist_safety_mode=1

After the ocean formation• 3.6 billion years of simple cells

(prokaryotes)• 3.4 billion years of stromatolites

demonstrating photosynthesis,SNOWBALL EARTH• 2 billion years of complex cells

(eukaryotes)• 1 billion years of multicellular life,

Snowball earth

Continental Drift: Creation of oceans

Do oceans change?___ how?_____________

___________________

World Ocean• Covers 70.8% of Earth’s surface• Four main basins—Pacific, Indian, Atlantic, Arctic• 1. Which ocean is the largest?_______• 2. Which ocean is between North America and

Europe?________• 3. Which ocean is Bordered by Africa, Australia, India?______________

Geology of the Oceans

• Continental crust vs. Oceanic crust: What is the difference?_______________________

Continental Drift• Magma & convection currents drive continental movement• Erupting magma– Midocean ridges– ridge systems

• Subduction zones:• __________________• Seafloor spreading:• __________________

Mid-Ocean Ridges

Ocean Basin

• Abyssal Plains and Hills

• Seamounts• Ridges and

Rises• Trenches– Island arcs– Marianna

Trench

Evidence for Continental Drift

• Fit of the continental boundaries• Distribution of earthquakes• Temperature of the sea bottom• Age of rock samples from the seafloor:

young/old• Analysis of core samples drilled through the

ocean sediments.

What is on the bottom of the ocean?

Rift Communities

• Rift communities, or deep-sea vent communities

• 1977• Food webs in absence of sunlight

Composition of Sea Floor

• Hydrogenous Sediment• Biogenous Sediment– Calcareous ooze– Siliceous ooze (glass)

• Terrigenous Sediment– mud

• Cosmogenous Sediment– Iron rich

Aliens of the deep• Watch the video and list any organisms that you can

identify and what criteria you used to identify them.

Work in groups 2-4