What do you mean by the statement,"After the Treaty of Versailles the value of German mark fell."?Pls explain how the value of a currency can fall.

1] MANY GERMANS HELD THE NEW WEIMAR REPUBLIC RESPONSIBLE FOR NOT ONLY THE DEFEAT IN THE WAR BUT THE DISGRACE AT VERSAILLES.
2] GERMANY WAS FORCED TO PAY COMPENSATION AMOUNTING TO 6 BILLION.
3]THE ALLIED ARMIES ALSO OCCUPIED THE RESOURCE RICH RHINELAND FOR MUCH OF THE 1920S.
4]GERMANY LOST ITS OVERSEAS COLONIES, A TENTH OF ITS POPULATION, 13% OF ITS TERRITORIES, 75%OF ITS IRON AND 26% OF ITS COAL TO FRANCE,POLAND,DEMARK AND LITHUANIA.