For such a compact country, Wales has had an incredibly varied geological history. It has seen several glaciations, endured arid desert conditions, been covered by deep oceans, and has undergone intense mountain building forces. Due to continental plate movements it has travelled widely across the globe. Starting in the high latitudes of the Southern hemisphere, it moved generally northwards, crossing the equator before reaching its present position. In Wales today can be found rocks representing all geological periods, except the Permian, Cretaceous and Tertiary.