Sea-Floor Spreading

Massive pieces of land that are part of the Earth's crust and upper mantle

• Tectonic plates
• Trenches
• Divergent boundary
• Continental shelves

___________ help explain why Earth is not getting any larger even though the tectonic plates are always moving.

• earthquakes
• subduction zones
• fossils
• volcanoes

The OLDEST seafloor is located? 

• Closest to the mid-ocean ridge
• Farthest from the mid-ocean ridge

True or False : Sea-floor Spreading adds new material to the ocean floor?

• True
• False

What happens when Subduction occurs?

• Parts of the crust fall into the mantle
• Parts of the crust fall into the core
• Parts of the crust fall into space
• None of these

What did scientists use to map the oceans floor?

• Echo-location
• Sonar
• Space Shuttles
• Animals

What are Mid-Ocean Ridges?

• A chain of underwater waterfalls 
• A chain of underwater volcanos
• A chain of underwater mountains
• A chain of underwater rocks

What is one piece of evidence of seafloor spreading? 

• scientist found animals at the bottom of the sea
• mountain rocks crashed into the ocean
• scientist found pillow shaped rocks like pillows

The oceanic crust _________ when it reaches the continental crust.

• sinks
• rises
• expands

New crust is always formed at the...

• mid-ocean ridge
• deep-ocean trench
• asthenosphere