Complex sentence: It was first visited in 1957 by a small party from Hallett Station, and was so named by the New Zealand Geological Survey Antarctic Expedition, 1957--58, because of its shape.
Split into simpler sentences: It was first visited in 1957 by a small party from Hallett station. So named by the New Zealand Geological Survey Antarctic Expedition (NZGSAE), 1957--58, because of its shape.