When the markets start to tumble, they will tumble rapidly and may move in many directions. There may be financial freezes maintained, such that the financial status quo at a given point in time and the cash value of moneys of different countries are not allowed to float freely. Its essentially like stopping an elevator from moving up or down. It simply doesnt move after that point in time. Black markets of course will develop, but they develop somewhat slowly, not overnight. So this kind of enforced freeze, in essence a martial law of the financial field, can be maintained for many months, even years, and be somewhat effective. This is a likely outcome. This is already happening on the stock market where a run on a stock is stopped by a closure of the stock markets. They cease the trading until some time has passed, and this is a forerunner of what is to come.