Complex sentence: Alfred Wegener, being a meteorologist, had proposed tidal forces and pole flight force as the main driving mechanisms behind continental drift; however, these forces were considered far too small to cause continental motion as the concept then was of continents plowing through oceanic crust.
Split into simpler sentences: Alfred Wegener, being a meteorologist, had proposed tidal forces and pole flight force as the main driving mechanisms behind continental drift. However, these forces were considered far too small to cause continental motion as the concept then was of continents plowing through oceanic crust.