...Many econo-gurus lay the blame for the Great Depression on the Federal Reserve tightening too soon, or not loosening credit enough, but this is nonsense: The Great Depression was the result of credit/borrowing (i.e. debt) outrunning the foundation that supports debt: productivity and income.
Piling more debt on a base that isn't expanding fast enough to support skyrocketing debt leads to a collapse of the feebly supported debt: borrowers default, asset prices crash as buyers vanish and lenders go bankrupt as the assets held as collateral are repriced.