Where are the earth's magnetic poles?
Deep within the earth, along an axis which 'wobbles' around the earth's axis of rotation. This causes the locations called 'Magnetic North' and 'Magnetic South' to shift relative to the locations called 'True North' and 'True South'. The magnetic polarities of the locations 'Magnetic North' and 'Magnetic South' are south and north, respectively.
Explain how the reversal of earths magnetic poles can be produce a calendar for part of earths history?
What do bands of rock on the seafloor showing alternating magnetic orientation indicate about the earths magnetic field?
The answer is in the question. Current in a conductor causes a magnetic field. A compass uses a magnetised needle to align with the earths magnetic field. Like poles repel, opposite poles attract. The magnetic needle in a compass will act like any other magnet and will be attracted to another magnet.
Magnetism leaves particles in molten metals lined up with north and south poles (magnetic poles, not the Earth's poles). Over time different layers of rock show that the N-S and S-N poles have switched, with S pointing in one direction and S pointing in a different direction depending on the age of the rock.
The Earth's magnetic poles do in-fact 'wander' over the years. Estimates put the movement of the North Pole at 34-37 miles (55 and 60 kilometres) per year. The magnetic poles are not always directly opposite each other. There is a good article on Wikipedia with more information - search for 'north magnetic pole'.
The magnetic axis is relatively unstable compared to the rotational axis. The magnetic poles move around quite a bit from decade to decade. In fact, geologists have discovered that the alignment of the molecules in some sedimentary materials shows that the north and south magnetic poles actually switch places every few tens of thousands of years.
The Earth's geographic poles are the points 90 degrees north and south of the Equator at which all lines of longitude intersect. The Earth also has magnetic poles near these points with which compass needles align themselves. The south magnetic pole is off Wilkes Land, Antarctica, about 1,710 miles from the geographic South Pole. The north magnetic pole is on Ellef Ringnes Island in northern Canada, about 870 miles from the geographic North Pole.
There are no stories that magnetism actually attacks ships. It has however, been observed, that there are magnetic anomolies in the area. The north and south magnetic poles of the earth, are not exactly at the poles, but close enough to be of use over most of the lower lattitudes. The earths magnetic poles can be affected by local rock formations, some actually are the reverse of the main poles, making a magnetic compass point…
I am not sure what you mean by widening. The Earth's magnetic field is a result of the fact that the Earth has a molten Iron core and the planet is rotating quite rapidly. The strength of the magnetic field in these circumstances is dependent on the speed of rotation. As the Earths rotational speed is slowing (due to the friction of the tides caused by the moon) the Earth's magnetic field is gradually weakening…