Rich soil to grow wheat, barley, and peas in the indus valley resulted from

The rich soil of Indus Valley resulted from the floods that occurred every year in the area. The water from the flood brought fertile soil with it. 
The settlements of Indus Valley were built on the river bank. The time for this civilization is around 2500 BC, and is known to have lasted for around a thousand years leaving behind a history of great civilization.

a mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics. this uplifting of the ocean floor occurs when convection currents rise in the mantle beneath the oceanic crust and create magma where two tectonic plates meet at a divergent boundary.a geomagnetic reversal is a change in a planet's magnetic field such that the positions of magnetic north and magnetic south are interchanged.