Tag Archives: colorado river

Genetic Analysis Splits Desert Tortoise into Two Species

By Guest PostJune 29, 2011Environment, Natureagassiz desert tortoise, arizona, army physician, california, california state university dominguez hills, colorado river, desert tortoise, dna evidence, endangered species act, fish and wildlife service, fws, genetic evidence, gopherus agassizii, gopherus morafkai, habitat preferences, j g cooper, kristin berry, Mexico, morafka desert tortoise, nevada, northern arizona, robert murphy, roy averill murray, san francisco earthquake, Smithsonian, species, us army fort irwin, usaf edwards air force base, usgs, utah

RIVERSIDE, Calif. – A new study shows that the desert tortoise, thought to be one species for the past 150 years, now includes two separate and distinct species, based on DNA evidence and biological and geographical distinctions.

This genetic evidence confirms previous suspicions, based on life history analysis, that tortoises west and east of the Colorado River are two separate species. (more…)

Ancient Colorado River Flowed Backwards

By Guest PostOctober 4, 2010Sciencearizona, california river, colorado river, colorado-green river system, colton formation, geologist, gulf of california, isotope, lead, mineral, mojave region, rocky mountains, southern california, steven davis, uranium, utah, zircon

Palo Alto, CA — Geologists have found evidence that some 55 million years ago a river as big as the modern Colorado flowed through Arizona into Utah in the opposite direction from the present-day river. Writing in the October issue of the journal Geology, they have named this ancient northeastward-flowing river the California River, after its inferred source in the Mojave region of southern California. (more…)