Prac Questions
Prac 1- Plates that separate
1. Explain how this activity relates to the spreading at the mid ocean ridges.
Plates are moving very fast. A weak fault line causes a huge valley to form and magma fills it. The magma cools and solidifies. Old rocks get pushed out the way by new ones.
2. Identify what in your model represents each of the following:
a) Ocean floor or plate- the tables
b) the water-The paper
c) The lava flow-coloured strips
d) gravity- Pegs
e) mid ocean ridges- The part of the paper that lifts up near thr crack between the tables.
f) the magnetic strips found in rocks parallel to the mid ocean ridges-
3. Describe what you noticed about the height of the paper as it emerged from the gap compared to the paper futher out.
The paper was higher in the middle near the crack between the tables and it went down as the paper went further out,
4. Identify which of the strips you coloured would be the for the oldest rock and which the youngest rock.
The strip right th the ends of ech paper would be the pldest rocks and the ones near the centre would be the new rocks.
5. Identify which of these strips would be the first to be swallowed by an ocean trench.
The oldest ones which were the ones furthest out would be the first to be swallowed by a trench.
Prac 2- Colliding Plates
1. Compare th above tests with plate tectonics.
These tests correspond with collision boundaries and scraping boundaries. Collision boundariesare where one plate collides with another. These are destructive boundaries since rock is melted here and is returned to the mantle for recycling. Scraping boundaries are where plates scrape along eachother. They are conservative boundaries since they conserve rock. They do not create or destroy it.
2. The stack of paper had obvious layers. Assess whether rock has layers, and of so explain why.
Rocks do have layers.
3. State which tests simulated the following collisions.
a) a continental plate with another continental plate- Test 1
b) an oceanic with another oceanic plate- Test 2
c) An oceanic plate with a continental plate- Test 3
4. Identify a place on earth where each of these collision types occur.
Places where these collision types occur are called fault lines.
