Complex sentence: Gale later suggested that this site may not have even been a stone circle at all, but might instead have been the remains of an Early Neolithic chambered tomb, but noted that "as nothing remains it is at the moment impossible to resolve".
Split into simpler sentences: Gale later suggested that this site may not have even been a stone circle at all, but might instead have been the remains of an Early Neolithic chambered tomb. He noted, however, that "as nothing remains it is at the moment impossible to resolve".