Past Climates…

Another time but the same place… A little history… after all, living things seem to have been around for a long time!

Before North America hosted its first humans, the Great Basin and much of the Mojave resembled a farmer’s field in springtime, newly plowed and furrowed. Valleys, called basins appeared as the earth’s crust was stretched, twisted, compressed, and simultaneously lifted and dropped over time, causing the higher ground on either side to take on the appearance of mountain ranges. The resulting and “basin and range” landscape looked much like a newly plowed field. When viewed from above as in the illustrations at left, this same valley-ridge-valley-ridge landscape is still evident in many parts of the world today.

Early Landscape of the Miocene (20 millions years before the present) http://jan.ucc.nau.edu/~rcb7/20moll.jpg

This Basin and Range” landscape has been modified, however, in the numerous geologic and climatic changes of the continent in the 5-10 million years before the present time (YBP), dating back to the late Miocene Epoch (illustrated in the following image).


The last significant period of climate change introduced an ice age and the storage of water in the form of glacial ice in the northernmost latitudes, and in the ancient rising of the High Sierra [a prominent Mountain Range in Central California].

These large bodies of ice began to melt 20-15,000 YBP, during what is called the Pleistocene Era, the most recent epoch of geological history (when humans were still stone-age hunters and gatherers). The furrowed “valleys,” filled with melting snow, formed finger-shaped lakes of various sizes, connected [from time to time] by rivers or streams at the ends of the mountain ranges. Small, minnow sized fish that lived along the margins of these water bodies and waterways were some of the first to discover that these lakes connected to another at the ends of the furrow-like valleys. They joined, one to another, end to end, until they could be found across most of the entire Basin and Range land and waterscape. Eventually, the warming trend that brought about the end of the last ice age also caused the slow “de-watering” of the land- and waterscapes, drying many of the connecting rivers and streams; it brought the eventual and slow demise of the basin lakes. The populations of minnow-like fish that were once seemingly free to “go with the flow”, mixing and interbreeding, when allowed, with other populations of the same species were now isolated from one another, each in its own dwindling “water world”.

As time passed and the laws of genetics and survival of the fittest prevailed, each minnow population began to demonstrate slight changes in appearance, breeding, and feeding habits. In the late 1800’s and early 1900’s, following the Gold Rush, naturalists began to study the fish in the “Great Basin” watersheds. By the mid-1930’s, over 13 varieties of minnow-like fish had been caught, preserved and described.

Since these fish were in the same family of carps and minnows as a common sports fish in Europe called “chub” (the Cyprinidae), that name quickly stuck. However, the Paiute Indians indigenous to the Great Basin landscape on the eastern side of the Sierra Nevada called the fish the “tuipag-^I”. A major food source of this people group, the fish’s name became “Tui Chub” in honor of the Paiute nation (speculation).

With the advent of genetic techniques in the late 1980’s, the “Tui Chub” of the Great Basin and Mojave have been classified into 13+ different subspecies. The Mohave tui chub (Siphateles bicolor mohavensis) is but one of those, the only native fish to the remaining Mojave “furrow,” the Mojave River watershed.