Across
- 3. an instrument for measuring the intensity of a magnetic field, especially the earth's magnetic field.
- 5. Changes in direction or orientation of the magnetic field of the Earth that have occurred from time to time.
- 6. Geology. the lateral movement of continents resulting from the motion of crustal plates.
- 8. a theory in geology: 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
- 11. a portion of motion of a tectonic plate that can be accounted for by its subduction. Plate motion is partly driven by the weight of cold, dense plates sinking into the mantle at trenches.
- 12. a proposed mechanism for plate motion in plate tectonics. Because mid-ocean ridges lie at a higher elevation than the rest of the ocean floor, gravity causes the ridge to push on the lithosphere that lies farther from the ridge.
- 13. is a linear feature that exists between two tectonic plates that are moving away from each other.
- 15. the hypothetical landmass that existed when all continents were joined, from about 300 to 200 million years ago.
Down
- 1. Geology. the process by which collision of the earth's crustal plates results in one plate's being drawn down or overridden by another, localized along the juncture (subduction zone) of two plates.
- 2. Geology. magnetic polarization acquired by the minerals in a rock at the time the rock was deposited or solidified.
- 4. a major geologic discontinuity or suture marking the juncture of lithospheric plates that have been joined by plate tectonics.
- 7. is a type of fault whose relative motion is predominantly
- 9. a line on an isotope ratio diagram denoting a suite of rock or mineral samples all formed at the same time. The slope of the line is related to the age of the rock or mineral suite
- 10. a process in which new ocean floor is created as molten material from the earth's mantle rises in margins between plates or ridges and spreads out.
- 14. a subsea chasm extending along the crest of a mid-ocean ridge, locus of the magma upwellings that accompany seafloor spreading.