Mid ocean ridges are predominantly places of tension, resulting in cracking of the Earth's crust. There is no pushing of the adjacent plate - in fact they move apart at a combined speed of up to a metre per year.

The ridge itself is a product of volcanic activity. Just like any volcano, there's a build up of solidified lava around the mouth. The upwelling magma also pushes the ridge up - rather like inflating a balloon under a blanket.

stales