Situated about 10 miles southwest of Denver, Colorado, the Pink Rocks Amphitheatre is among the most beloved live performance venues on this planet. From classical symphonies and the Beatles to John Denver and U2, the checklist of performers who’ve performed Pink Rocks because it started internet hosting live shows in 1908 is almost so long as the amphitheater’s 2.5 miles of seating.
The rationale for its excessive regard? A mix of naturally occurring geology, man-made structure and practically excellent acoustics. However let’s begin with the rocks themselves, that are tons of of thousands and thousands of years within the making.
Benjamin Burke, an affiliate professor on the Colorado Faculty of Mines, explains that Pink Rocks is actually an historic delta — a 300 million-year-old accumulation of sedimentary rock that after belonged to what’s referred to as the ancestral Rockies. Like the present Rockies, these mountains had been very tall. However the forces of abrasion (wind, precipitation and temperature) labored to carry silty, sandy, muddy waters downstream alongside a collection of huge rivers.
These supplies created quite a few deltas within the space, together with the Flatirons area west of Boulder, Roxborough State Park close to Littleton, and the Backyard of the Gods to the west of Colorado Springs. Collectively, Pink Rocks and the remainder of these areas kind the Fountain Formation. Although the composition of the area varies, the stuff that types Pink Rocks is especially sandstone of the poorly sorted selection; it ranges from sandy grains to bigger cobbles, Burke says.
After historic storms despatched mud and sand streaming down the mountains, they slowly compressed into rock by means of the geologic strategy of lithification. Subsequent erosion of this rock carved out the world the place the amphitheater sits right now. “The 2 rocks on both facet of the amphitheater are a bit extra resistant [to erosion], for no matter motive,” says Burke, referring to Ship Rock — the enduring pink stone face to the viewers’s left — and Creation Rock to its proper. Each beautiful, tilted vertical rock formations are taller than Niagara Falls.
(Credit score: Megan Mahoney Pictures/Shutterstock)
The highest of Pink Rock’s seating space, which supplies the amphitheater’s finest views of Denver and the encompassing panorama, features a bronze plaque marking the spot the place Fountain Formation rock collides with the 1.7 billion-year-old, Precambrian rock that types the underside of the Denver Basin, Burke says. The older rocks on this space had been mined for silver and gold throughout varied valuable steel rushes between about 1858 and 1893, he provides.
In 1911, three a long time earlier than it opened to the general public in its current architectural kind, world-famous Scottish opera singer Mary Garden carried out the primary solo live performance at Pink Rocks. She remarked that she’d by no means heard extra excellent acoustic properties at any opera home on this planet.
Burke, who attends not less than one present a yr on the venue, admits that he isn’t an audio engineer. However he presents a primary rationalization: Each Creation Rock and Ship Rock, mixed with the stage infrastructure constructed straight in entrance of the disc-shaped rock referred to as Stage Rock, create a super switch of sound.
“The constructing and the rocks earlier than it actually ship the sound outwards to the viewers,” he says. “The [rock] partitions primarily preserve that sound in, with out there being a roof the place there’d should be sound deadening. So, you get a variety of projection outwards with out the reverb, if you’ll, of the enclosed house for [sound] to bounce round in.”
The position of the rocks within the acoustic profile is probably going owed extra to measurement and angle than composition, he continues. Whereas sandstone usually lacks any particular acoustic powers, it’s potential it may need some marginal sound-absorbing properties in comparison with tougher rock like granite. “On the entire, rock continues to be rock,” Burke says. “The actual fact these partitions are there permits for the sound to remain within the amphitheater however not get trapped and bounce forwards and backwards.”
The Seaside Boys carry out in live performance on July 09, 2012. (Credit score: TDC Pictures/Shutterstock)
There’s additionally the elevation facet. At 6,450 ft, sound truly travels barely slower than at sea degree, due to each air strain and temperature. Whereas that in itself isn’t noticeable to the human ear or mind, a singer’s efficiency in thinner air is likely to be.
“It’s all the time enjoyable, as a Denver native, to see performers come up from sea degree,” Burke says. “If the performer doesn’t know what they’re in for, that does considerably change the supply a bit of bit. They find yourself being a bit breathless.”