The earth magnetic field can be likened to a bar magnet with a North and South pole. It originates from the movement of molten iron and nickel in the outer core.
At every point in time, the magnetic field orientation can change. We must note that the magnetic north lies close to that of geographic north axis of the earth.
Around the mid-oceanic ridges, new materials are brought to the surface. These new materials can contain magnetic minerals such as haematite which are capable of being magnetized as a result of the prevalent magnetic field of the earth. As different materials are brought up, the magnetic minerals preserves the details of the magnetic field at that point in time. Using this information can know the orientation of the magnetic field at any point in time if the magnetic history chart of the earth is constructed. Oceanic ridges becomes older as they move away from the divergent margins.
physical process whereby the colonizer takes over another place, putting its own government in charge and either moving its own people into the place or bringing in indentured outsiders to gain control of the people and the land.
The Gold Rush was the largest mass migration in U.S. history. In March 1848, there were roughly 157,000 people in the California territory; 150,000 Native Americans, 6,500 of Spanish or Mexican descent known as Californios and fewer than 800 non-native Americans
