Question

Explain how the differing ages of rocks on the ocean's floor supports the theory of plate tectonics. In your answer, be sure to address the topics below.

A. Changes in the earth's magnetic field

B. Patterns of polarity in the seafloor

C. The thickness of sediments and the age of fossils in the seafloor

D. How this data supports the idea of seafloor spreading

Answer 1

A)The earth's magnetic field changes in a regular geological time interval.

The earth's magnetic field originated largely due to rotation of earth and liquid outer core rotation acts like a dynamo.Earth's outer core composed of ionized charge molecules when they rotate charge molecules present in outer core moves,acts like dynamo creates magnetic field.

This magnetic field line moves north pole to south pole but do not intersect.

Earth rotates from west direction to east direction, so magnetic field is drifting towards west. At current scenario earth magnetic field is westward drifting.

Earth magnetic pole have been changed several times today's north pole once upon time south pole and vice versa.

B)Pattern of polarity have been greatly affected magnetic pole.

For example at mid oceanic ridge sea floor is spreading.

The upheaval of magma from asthenosphere when crystallization occurs, due to thermal remnant magnetism those are aligned magnetic pole.

These have been recorded in rocks of ocean sea floor.

There are various epoch of normal magnetic and reverse magnetic alignment data present.

There are just like alternating magnetic polarity. This has been shown in figure

C)The ages of sea floor get more older from ridge axis of mid oceanic ridge.

Near spreading ridge axis the sediment age usually younger as we go away from this ridge it gets older.

The more thickened crust or sediments implies more older rock and it has transported more.

D)Same thing has been explained in figure and above that sea floor crust moves laterally, the older rock found distance from ridge axis and younger rock found in near spreading centre.

These rock have been aligned according to magnetic north pole and south pole at different geological epoch.

Just previous magnetic epoch was Brunhes normal polarity 1 million year back.

Here alternating normal and reversal magnetic polarity have been recorded. There have been of data of magnetic polarity data of 5 million ages.