landforms created by plate techtonics Flashcards
What is a constructive plate boundary
A boundary where two tectonic plates diverge (move apart), creating new crust
What are the two types of divergence at constructive margins?
Oceanic divergence (sea-floor spreading) and continental divergence (rift valleys).
What happens when oceanic plates diverge?
Sea-floor spreading occurs, forming mid-ocean ridges like the Mid-Atlantic Ridge.
What geological features are created by sea-floor spreading?
Underwater mountain chains, fault lines, volcanic eruptions, and sometimes volcanic islands.
Why do earthquakes occur along mid-ocean ridges?
Because different sections of the ridge move at different speeds, causing stress along fault lines.
What happens when continental plates diverge?
The crust stretches and collapses, forming rift valleys like the Great African Rift Valley.
How are rift valleys formed?
The lithosphere splits sideways, creating parallel faults that collapse into deep, wide valleys.
Where can the youngest rocks on Earth be found?
At constructive plate margins, where magma rises and solidifies to form new basalt-rich rock.
What landmass was formed due to constructive plate activity?
Iceland, which sits on the Mid-Atlantic Ridge.
What happens at a destructive plate boundary?
Two plates collide, creating landforms such as fold mountains and ocean trenches.
What forms when two oceanic plates collide?
The denser plate subducts, forming a deep ocean trench (e.g., the Mariana Trench).
What is an island arc?
A chain of volcanic islands formed when magma from the subducted plate rises to the surface.
Where are two well-known island arcs located?
South of Japan and the Lesser Antilles in the Caribbean.
