Meeting Report: Utah and Arizona — a Love Affair

Date: 
12 October 2012
Speaker(s): 
David Edwards

Following the AGM of Dumfriesshire and Galloway Natural History and Antiquarian Society, David Edwards was introduced as the speaker for the first meeting of the new season. A Fellow of the Royal Geographical Society, he has served as a lecturer in Earth Sciences and he is well-travelled. For instance, he led an expedition to Botswana.

His topic on this occasion was 'Utah and Arizona — a love affair', in preparation for which he sifted through his 900 slides to select many remarkable landscapes. On his first encounter he was unexpectedly bowled over by the Grand Canyon, which in USA terms is a small National Park. He just had to go back and was lucky enough to be appointed as a ranger.

The Grand Canyon has several advantages. Low rainfall inhibits vegetation and so its dramatic outlines are visible. Although there are 5 million visitors a year it is still possible to derive a wilderness experience. It has a great diversity of flora and fauna, most unexpected of which was to find the tree frog there in the desert and the most dangerous, the pink rattlesnake. There are four climate zones from the top at 10 thousand feet, where snow can be lying, down to base level.

In order to understand the passage of time regarding developments on earth David suggested taking a year and equating each month to 375 million years. By March 2nd the oldest known rocks had formed. It was July before oxygen began to accumulate in the atmosphere and mid-July before the Grand Canyon's oldest rocks took shape.

All continents at or south of the Equator had formed by October 4th and by the 12th the climate and oxygen content were familiar to that of today. November saw large animals and plants coming to life and sandstone forming.

On December 11th the youngest Grand Canyon rocks were created and December 15th saw the rise of the dinosaurs, a most successful group. There are no dinosaur fossils because they are not old enough. They became extinct 135 million years ago. A meteorite might have been the cause because one set off a fire in the Grand Canyon 6 million years ago.

Modern humans appeared only at 24 minutes before midnight, that is 250 thousand years ago. One second ago we began altering our environment when the Industrial Revolution took place and thereafter we introduced rapid change. Man ought to recognise that we have a responsibility of stewardship of the earth.

The above outline of developments presents a challenge to the beliefs of creationists because they can't go past 10 thousand years ago. They think that the earth was created for man.

David went on to show the many magnificent features of other canyons and national parks. Bryce Canyon is carved purely by intense rain storms in which 5–6 inches fall in one go and cause a mobile, changing landscape created by incredible landslides.

In Zion National Park the peaks are twice as high as Ben Nevis; Utah has the third highest number of endemic (i.e. they are found nowhere else) plants in the USA; and it would take a trip from the Canadian border to New Mexico to encounter the same biodiversity.

The Arches National Park is characterised by over 2,000 arches of fins of rock. Arches over water in time become a bridge instead. A fault in the rock allows a crack to develop; water flows down and erodes the rock and creates a deeper chasm. The rocks on both sides of the canyon don't line up.

Chiricahua National Park, near the Mexican Border, is the most dangerous. Three rangers died in 2008. Drug peddlars are the reason.

The dilemma faced by all National Park authorities is that, in encouraging increasing numbers of visitors, they can destroy nature's wonders that they came to see.