“Alhambra Rock juts up northeast of Monument Pass, an errant monument with a very unusual origin. It is one of several diatremes in the region. It formed about 30 million years ago when a gas-driven vortex of material blasted upward from below Earth’s crust. It contains pieces of Earth’s mantle and of the rocks it punched through. Possibly moving faster than the speed of sound, the material probably followed old Precambrian faults. The rock is kimberlite, the type of rock that diamonds occur in, though none have been found here.”
(Williams, Felicie; Chronic, Lucy; Chronic, Halka. Roadside Geology of Utah . Mountain Press Publishing Company. Kindle Edition.)
This is a BIG claim! The speed of sound is 767.27 mph – Woah!
The guidebook has this paragraph and just as quickly moves on to the next features – but this seems quite significant to me – is that really possible? That is a significant claim to say that over long periods of time, gas built up enough without dissipating in any other direction to be able to blow this huge chunk of rock through the crust at the speed of sound.