How did the location of the Battle of Somme, Verdun and Ypres factor into the amount of lives taken, as well as the impact of these battles?

All of the mentioned battles took place on a relatively small area, compared to the amount of lives and the amount of mortar fire that was taking place. Due to this, areas with a very small radius became a "killing ground" for incredible amounts of soldiers which had not yet been seen before at all in the history of mankind.