If there's too little cash, people will start hoarding and the economy will quite literally grind to a halt as people are reluctant to part with money.
Going back to bartering is a great way to induce a depression.
Bartering often comes after a depression already exists. When liquidity drops to zero, people will develop their own money. Bottles of Tide, gasoline, cigarettes, etc.
Going back to bartering is a great way to induce a depression.