A massive magic ritual involving the nation's greatest spellcasters utilizing an entire city as their focus, either through miscalculation or sabotage, inadvertently open a massive portal into the center of the plane of fire! Oh no!
This incredibly intense gout of arcane flame erupts from the portal like a geyser. The city and its inhabitants, at least those closer to the epicenter, are vaporized. The flames don't stop pouring out of the portal for days (weeks?).
Would this sustained source of fire be enough to turn a sizeable region from moderately forested to
a desert an arid, sandy region? Bonus points if you can say whether it is possible for the heat to be so intense at the epicenter that it could become "glassed" (for lack of a better word).
EDIT: To make my question a little more specific, could magically-created, high intensity heat and flames do enough damage to the earth around it to turn a temperate/forested area into a sandy/rocky, arid region comparable to something like the Gobi desert or some of the deserts in Australia or would nature eventually do its best to revert the area to what it was before?