what is palaeomagnetism

Palaeomagnetism deals with the past magnetic states of the earth. In the 1900's geographers were interested in the mid Atlantic ridge, its on a constructive plate margin, meaning the crust further away from the mid Atlantic ridge is older than that near it. In the crust are particles with magnetic properties like iron and nickel that pointed that aligned to the north pole. They noticed that in bands of roughly 500,000 years of crust, the direction the iron and nickel alternated between north and south. They were able to infer that on a roughly a 500,000 year cycle, the earths poles flip. this shows that the earths poles have not always been fixed and are likely to change within the next 500,000 years. you will need this for the natural hazards module of geography. Here is a diagram to help you visualise palaoemagnetism across the Atlantic.