Alex Janssen

2. proposed mechanism for plate motion in plate tectonics
4. the portion of motion of a tectonic plate that can be accounted for by its subduction
5. a feature that exists between two tectonic plates that are moving away from each other
7. the lithosphere of the earth is divided into a small number of plates which float on and travel independently over the mantle and much of the earth's seismic activity occurs at the boundaries of these plates
10. hypothetical landmass that existed when all continents were joined, from about 300 to 200 million years ago
11. instrument used for measuring magnetic forces, especially the earth's magnetism
12. Changes in direction or orientation of the magnetic field of the Earth that have occurred from time to time
13. sideways and downward movement of the edge of a plate of the earth's crust into the mantle beneath another plate
14. line on a diagram or map connecting points relating to the same time or equal times

1. actively deforming region where two (or more) tectonic plates or fragments of the lithosphere move toward one another and collide
3. large elongated depression with steep walls formed by the downward displacement of a block of the earth's surface between nearly parallel faults or fault systems
6. study of the magnetic record in rocks
7. strike-slip fault that offsets a mid-ocean ridge in opposing directions on either side of an axis of seafloor spreading
8. gradual movement of the continents across the earth's surface through geological time
9. process of the ocean floor moving away from an ocean ridge