What caused the crash in the early 70’s before the embargo?
What I remember is the devaluation of the dollar, which occurred at roughly the same time as OPEC’s changing of the price of oil.
Prior to the change in oil price, if I recall my history correctly, oil was going for something under $3.50 per barrel, although I am not certain of Berri crude.
At that time, I knew someone who worked for the CEO of one of the ‘Seven Sisters’ of oil companies. He spoke of a meeting in Canada, during which time, an agreement on price fixing took place.
The Yom Kippur war also happened at this time.
It was a conflagration of events.
Oil Price History and Analysis
http://wtrg.com/prices.htm