McLennan Hills (also Te Aponga o Tainui) is one of the volcanoes in the Auckland Volcanic Field. It was a group of cratered scoria mounds up to 45 m high, before it was quarried away. A 1940 aerial photo (in Searle's book) shows a crater around 100 m wide, one around 50 m wide, and 2 or 3 smaller craters. The photo also shows terracing on the hills' slopes consistent with it being the site of a pā. The former quarry site is now used for greenhouses.
References
McLennan Hills Wikipedia(Text) CC BY-SA