"and that the abandonment of the gold standard is at the root of the matter"
Gold bullion from the safe of the National Bank of Poland
Creative Commons AttributionGold bullion from the safe of the National Bank of Poland - Credit: covilha

The gold standard defined the value of a currency according to the cost of gold: setting the gold price at, for example, £100 per ounce would mean that £1 was worth 100th of an ounce of gold, giving a fixed exchange rate. In 1933, US President Roosevelt banned private purchases of gold, effectively rescinding the Gold Standard Act which had been in place since 1900, in an effort to stimulate the economy and end the Great Depression (1929-1933).

Further reading:

Protectionism wasn't the problem, Stephanie Flanders, BBC Economics Editor

The Wall Street crash 1929-33, Keith Spencer, League for the Fifth International