Garry has found there has been a major rock fall at the back of the Chasm, right on the abseil line. A block the size of a large refrigerator plus smaller stuff. He reckons the whole back of the chasm may be unstable and is warning everyone to stay clear till it is looked at. Spread the word if you can for climbers to be extra careful and to inspect the area  from below to assess the situation before committing to an abseil down from Northern Buttress.