300 ft deep sinkhole, Portugal

At first the sinkholes went down 30-40 feet, but I said they will get deeper going down several miles eventually. Here is a pic of one in Portugal that goes down 300 feet. SW (www.stuartwilde.com) http://sicnoticias.sapo.pt/pais/2013/04/09/cratera-com-100-metros-de-profundidade-em-marvao