Answer:
When the surface folds, or that's what I think... I learned it last year, so it is not fresh but when earthquakes occur they can maybe create folds, where fold mtns. can form!! So for example, if you fold and fold a piece of paper it soon is a multiple layered paper (if you were trying to compare it to a mtn.)!....:D PLZ I beg of you my best friend died a yr. ago and he has a Fb acc. sooo plzz go to Tsim Fukis and like him and put a nice comment. He was affected with progeria, a rare disease, so plz i beg of you, he was an awesome friend, with many loving family members. HOPE YOUR SOUL LIVES ON BRO!! R.I.P!!