Question

1. which cross section best represents the convection currents in the mantle beneath the peru - chile trench?

(1) diagram of trench and mantle with convection currents
(2) diagram of trench and mantle with convection currents
(3) diagram of trench and mantle with convection currents
(4) diagram of trench and mantle with convection currents

1. the country of iceland would be closest to the

(1) mohns ridge
(2) reykjanes ridge
(3) mid - atlantic ridge
(4) east pacific ridge

Explanation:

Question 6

Step1: Recall Convection Current Logic

Mantle convection: cold (dense) material sinks, hot (less dense) rises. At a trench (subduction zone), one plate subducts, so mantle flow should have a downward component near the trench.

Step2: Analyze Each Diagram

• (1): Currents have upward between them, but direction near trench? No, subduction needs downward.
• (2): Left current down, right current up? No, subduction zone: the mantle current should have the sinking (downward) near the trench. Wait, no—at subduction (trench), the overlying plate is subducting, so mantle convection: the current near the trench should have downward (sinking) on the subducting side? Wait, no, the Peru - Chile Trench is a subduction zone (oceanic plate subducting under continental). Mantle convection: the current below the trench should have the cold material (from the subducting plate) sinking, so the convection cell near the trench should have a downward flow at the trench. Wait, looking at the diagrams: in (3), the left current is upward? No. Wait, maybe I got it wrong. Wait, the Peru - Chile Trench is a convergent boundary (subduction). Mantle convection currents: the current below the trench should have the flow such that the material is moving towards the trench (downward) because the subducting plate is pulling or the mantle is sinking there. Wait, let's re - examine the arrows. In diagram (3), the left current has arrows going up, right current down? No. Wait, the correct logic: at a subduction zone, the mantle convection current should have the downward motion near the trench (because the subducting plate is going down, so the mantle above it? No, mantle is below the lithosphere. Wait, maybe the key is that in a subduction zone, the two convection cells: the one on the subducting side (oceanic) and the overriding (continental). Wait, the Peru - Chile Trench: the Nazca plate subducts under South America. So the mantle convection below: the current should have the downward flow near the trench (where the plate is subducting). Looking at the diagrams:
• Diagram (3): The left cell has arrows going up, right cell down? No. Wait, maybe the correct answer is (3)? Wait, no, let's think again. Wait, the convection current direction: hot material rises, cold sinks. At a trench, the subducting plate is cold, so the mantle above (or below?) would have sinking. Wait, maybe the correct diagram is (3) because the arrows near the trench are downward? Wait, no, in diagram (3), the left cell's top arrow is towards the trench, and the middle arrow is downward. Wait, maybe I made a mistake. Alternatively, the correct answer is (3). Wait, no, let's check the options again. Wait, the Peru - Chile Trench is a subduction zone, so the convection current should have the downward motion at the trench. So the diagram where the current near the trench is downward. Looking at the four diagrams:
• (1): Middle arrows up.
• (2): Middle arrows up (left) and up (right)? No.
• (3): Middle arrows down.
• (4): Middle arrows up.

So the correct one is (3).

Step1: Recall Plate Tectonics of Iceland

Iceland is located on the Mid - Atlantic Ridge, specifically the Reykjanes Ridge is part of the Mid - Atlantic Ridge and is very close to Iceland.

Step2: Analyze Options

• (1) Mohns Ridge: Not a major ridge near Iceland.
• (2) Reykjanes Ridge: Part of the Mid - Atlantic Ridge, very close to Iceland.
• (3) Mid - Atlantic Ridge: Iceland is on the Mid - Atlantic Ridge, but Reykjanes Ridge is a segment closer.
• (4) East Pacific Ridge: In the Pacific, far from Iceland.

So the closest is (2) Reykjanes Ridge.

Answer:

(3)

Question 7