The photograph to the right is a classic example of a volcanic neck . It is located on the Maverick Drive between Panther Junction and Ross Maxwell Drive on the north side of the road. Notice from the photograph that the volcanic body is slowly eroding away, leaving the more resistant igneous neck exposed. The photograph to the left displays a massive volcanic neck that is surrounded by a layer of tuff. Scattered throughout the tuff is scoria, a blackish red igneous rock with many large vesicles.
Vesicles are chambers of gas that get trapped in a rock while it is cooling.
This volcanic neck is located a few miles south of Tuff Canyon on the west side of the road. A few volcanic vents peek up from the tuff surrounding the huge neck. These vents were once underground veins of molten rock. Peeping up from the tuff flow described above, this volcanic vent resembles petrified wood both in texture and in appearance. When molten rock cools rapidly, it expands and often this results in cracks on the surface of the rockface.