Bryce Canyon is the third National Park we’ve seen these past few weeks. Grand Canyon is a geological feature carved over 6,000,000 years by the Colorado River and its flash floods with sporadic tinkering from volcanic eruptions. Zion is a middle-aged canyon created by the much smaller Virgin River which began its work about 2,500,000 years ago. Bryce has no river but was formed by “differential erosion” and “ice wedging”. The former results from varying degrees of rock hardness and vulnerability to acid rain, formed naturally for a billion years by rain combining with carbon dioxide to form weak carbonic acid, which is good at dissolving limestone. Ice Wedging is the same force that in freezing weather breaks water pipes, pavement, and rocks. Bryce has around 200 freezes and thaws annually, and over a few million years a lot of rock will break up, fall, and wash away after major rainfalls. That’s Bryce’s erosion.
The fossil record at GCNP is limited to the oldest life forms, plants and trilobites. Zion’s top layers of rock are more recent but are mostly footprints of early dinosaurs. Bryce is younger still, and finds here include a fossil skull of a Deinosuchus, an armored crocodile that grew to 40 feet in length and weighed eight tons. 75,000,000 years back that bad boy was the apex predator of swamps and lakes, capable even of taking down the largest dinosaurs.
All these parks have peaks, plateaus, and buttes created by tectonic plate movement and uplift, and all were once beneath a vast ocean. All had similar layers of sedimentary rock. Much later came the erosion, and the formation of these three very different canyons. Bryce is not a canyon but is a series of sandstone/limestone amphitheatres, plateaus, arches, and hoodoos (columns or pinnacles).
In April 2013 we published Faraday’s Cage, perhaps our most popular post ever. It explained the phenomena of lightning strikes having no impact on beings within closed cages made of conductive materials, such as cars, planes, and trains. Yesterday at Bryce we took a free, four-hour bus tour called “Rainbow Point”. Our driver narrated it, and showed us a fine specimen of one of North America’s hardiest plants, the Limber Pine. Its younger branches can be tied into a knot and untied without damage, and it actually prefers soil so bad that nothing else can grow there. Lightning usually kills trees instantly by boiling their sap with the steam blowing ‘em up. This pine has a big lightning scar, and according to guide Spike, the tree lived because it had been raining a while before the strike. “Dry strikes always kill a tree; they usually survive a wet strike.” Water is a good conductor of electricity. In a wet strike the tree, a non-conductor, is encased and given some protection by that water. The cage effect carries most of the juice to ground with minor damage to the tree.
I sure miss Carl Sagan and Mr. Wizard: they made science so interesting!
Another thing: Bryce is one beautiful park.