Continental Drift
Lecture 4 There is evidence of continental drift via the distribution of fossils and matching geologic units.. Matching mountain belts as well. The fit of continents and glacial deposits. by Wegener’s evidence for continental drift.
Bathymetry during WWII sonar recorded many discovered on the surface of the ocean floor. Abysmal plains, mid ocean ridges, continteal shelves, trenches, and seamounts
Hess/dietz came up with the idea of sea floor spreading. Through rising magma, subduction, and mantle.
OCEANIC CRUST - layer of sediments thicker near continents, mostly basaltic, heat flow is higher near mid ocean ridges, distribution of earthquakes In the world.
Earth’s magnetic field
magnetic and geographic north are not the same. Roatation of the death cases swirls in liquid core ,magnetic poles can migrate.
Side Step: Earth’s magnetic fields. Magnetic and geographic nmorth are not the same. Roatation of earth causes swirls in liquid core. Magnetic poles can mirgrate.
Lecture 4
Different locations on earth have unique magnetic signatures.
In a succession of rock layers, magnetic north and declination may vary. Possible explanations cam be polar wander or continental drift.
Each continent records unique apparent polar wander paths.
magnetic striping is symmetrical.
Earthquakes bands prove sea floor spreading
Hot spot theory
Created by the rising hot solid rock from the bottom of the mantle. Stops at the base of the lithosphere, not crust. Plumes are stationary, they do not move.
Subduction always causes volcanoes