The Creosote Bush (Larrea divaricata) is a tough, scraggly, shrub which endures droughts very well, and has flowers and small hairy fruits. It is presently found in the United States over thousands of square kilometers from Southern California to South Texas, as well as in Mexico and South America. It appears to have been designed to thrive in high temperatures and dry climates such as those found in the Chihuahua, Sonora, and Mohave Deserts.
The bush is interesting to creationists because it seems to show that the area has dried recently, possibly since the post flood glacial time. One evidence was the contents of nests of pack rats. Old nests have been dated by Carbon-14 to 40,000 years before present, and, though creationists dispute the absolute dates, the dates assigned to the nests were considered to at least show relative chronology as to which nests were older or younger than others.
The botanist cited by George Howe, Philip Wells, who presumably would not accept a creationist chronology, found that pack rat nests, or middens, that dated from 20,000 years to 11,500 years before present did not contain plant pieces from deserts but rather had evidence of forests of pines, junipers and oaks. Mr. Wells would put the time from 20,000 to 14,800 before present as the full glacial age, and after about 11,500 years before present would be a transition time where desert flora were invading the southern US. By 4,200 years before present, Mr. Wells found evidence of Creosote bush and Ocotillo in the middens examed. Though creationists would likely disagree with the assumptions of Carbon-14 dating, the progression from forest to desert fits well with the creationist idea that deserts formed after the Flood. It is interesting that one nest had parts of the Creosote bush that dated to both 2,700 years and parts of Junipers dated to 11,000 years before present both in the same nest.
Since the South American Creosote Bush is separated from the Mexican desert by a wide stretch of tropical forest, how could the Bush migrate to a desert that was forming after the ice age? Mr. Wells suggested that the Golden Plover, who annually migrates from Argentina to Alaska each year, could have carried some Creosote Bush seeds. This way the plant could invade an area, and eventually take up thousands of kilometers.
- Wood Rats, Plant Fossils, Plovers, and the Origin of Creosote Bush Deserts by George Howe. CRSQ 32(4):221-224. March 1996.