I've read that. Rocks rubing together under high presure....and it's been proven in the lab that it can happen.
And even more interesting is the 'Expanding Earth' theory..
The short version.. the core of the earth is a dynamic, molten object - and has a problem cooling off because of the crust of the earth, and gravity keeping it contained. This creates a reactor effect, where less dense elements are created and they push upward and outward, including hydrocarbons such as Petroleum, and natural gas. These lighter elements actually have pushed the surface of the earth outward, and over time have caused (and continue to cause) the planet to enlarge.
In short - Pangaea was a mega-continent on a mini earth, and it broke apart from internal forces as lighter elements rise from the core - like the way the crust on a loaf of bread fractures as it rises while baking.. ANd if this theory is correct, there will be more petroleum made by the earth as long as its core continues to be active.