I have been reading a book, The Medieval Machine, that says that during the so called Dark Age, there was something of an industrial revolution in Europe. For example, there were a large number of water and wind mills.

The book also tells how the use of the heavy plow made a big difference for places with heavy soil. Unfortunately, the book does not give a lengthy description of how it works. I checked the Web and am still confused how it worked.

There are 3 parts to the plough- coulter, plowshare and mouldboard. I believe that the coulter is in the front and is like a spike used to cut the soil. I found a description here . I would appreciate it if someone could explain this in simple terms.