Cove Fort Cinder Cone

The areas to the west of the freeway from Fillmore to Manderfield is known as the Black Rock Desert. It is covered in dark red, brown, and black basaltic lava flows, the oldest being around one million years old, and the youngest being 600-800 years old (the Ice Springs lava flow, youngest in Utah). The prominent hill east of I-15 near Cove Fort is a basaltic cinder cone, less than 12,000 years old, known as the Cove Fort Cinder Cone. Basalt is an iron-rich volcanic rock, which can erupt in lava flows (as in Hawaii) or spatter out of a vent and create a cinder cone. Basaltic rock often has numerous rough edges that look like popped bubbles. These "bubbles: were created when small pockets of gases were trapped while the rock was cooling from a liquid (lava) to a solid (the basalt as you see today).
Thanks, Keryn, for this information!

Lava rock is all along the highway that was used to build the Fort.