Complex sentence: In the 1930s and the 1940s several peat mining companies came into prominence; 6 meters deep of peat, covering an area of over 2 km² was cleared away.
Split into simpler sentences: In the 1930s and the 1940s several peat mining companies came into prominence. During this time 6 meters deep of peat, covering an area of over 2 square kilometers was cleared away.