Mt Elephant is a large breached scoria cone with a lava dome and surrounding lava flows.
Mt Elephant dominates the countryside around it, and driving up to it from the east is quite an experience. The walk up to the crater is fairly easy, with the walk up to the highest point harder, but well worth the effort.
The cutting on the northern side that give vehicular access to the crater cuts through the scoria that makes up Mt Elephant, and you can see lava bombs and layering. If you are lucky, you can find some nice cracked olivine rocks on the walk up.
Once you are in the crater, you can really feel the immensity of the mountain, surrounded on all sides by the walls. The bottom of the crater is lower than you are, and the lava dome is quite visible slightly to the back of the crater.
The walk to the summit is up the rim to the right, and you pass over what appears to be some slipping of the wall down into the crater. The summit gives an amazing view of the surrounding country, and the lava flows are quite evident, especially to the south.
We walked along the crater, stopping at the spatter ramparts on the southern end before proceeding down into a small breach on the eastern side. The path then takes you back down into the crater. We proceeded down to have a look at the lava dome, which is made up of much larger rocks that have split and crumbled.
The local group that owns the land of the sight do a great job, although the amount of interpretive material is limited. They (and the Wikipedia article) claim the age to be about 5-20,000 years old, but to us it feels much more like the age of Mt Rouse, somewhere greater than 100,000 years old. The erosion of the cone and the lava flows don't feel as fresh as Mt Napier, and that has been dated as older than 26,000 years, and resemble more closely those of Mt Rouse.