What did southern CA/Arizona/Nevada look like?

I've done a tiny amount of research and I think that the drive from Los Angeles to Las Vegas is nothing but Creosote due to overgrazing way back in the day. Anybody know what it looked like before that?

When the spanish explores first travelled through the Los Angeles basin, they noted evidence of fires, drought, earthquakes and floods everywhere, and said that it was definitely not a location suitable for human settlement.  Other than that, I imagine it was quite nice. 

The coastal area from just North of Los Angeles to Northern Baja Had more Native Americans per square mile than any other part of the North American continent. Probably no part of the US has been changed more by human habitation than this area. Originally it had a very shallow water table from foothills runoff which came to the surface in many places resulting in rivers, ponds and swampy areas. This, combined with the estuaries where rivers met the sea resulted in an easy and year round food supply.
The first European settlers immediately began using this water table for farming and irrigation till it was depleted and the area now is coastal desert where water cannot be imported from Northern California. If humans were removed from the equation it would probably return to its original state in only a few years.

Vast grasslands/savannahs with many creeks and springs.  A tremendously lush and productive area, much of it.  Especially right along the coast, as hoodat says.

Much of the "desert Southwest" was this kind of lush grass/tree/water mix, including my region.  100-300 years of cattle ranching has  changed it dramatically.

I little while back ago I read a very interesting paper on the prehistoric grazers of america. It made me re-think the notion of just looking back before the European arrival to see what "prestine" was. About 14,000 or 17,000 years ago there was a mass extinction of many megafauna that used to roam America. Yes, they found camels, horses, mamoths, and mastadons in our deserty southern california. Odd seeming since now the land can barely hold 1 cow every 5 acres (in some places). Scientist wonder to this day what caused the mass extinction. Was it really climate change? If it was, how come these creatures survived many other climate changes no problem. This was not their first ice age.

What else happened just before this time is that the old ice barrier preventing asian flora, fauna (including humans), disease, and pests melted and all these new species entered the Americas. The giant sloth never stood a chance against these new settlers. Neither did much of the megafauna. So the balance that was achieved during the time the megafauna dominated ended...but was a new balance ever achieved? What did megafauna do to the environment? Well, some hunted animals while others grazed or browsed plants. So, as the megafauna population dropped, the plants likely became decadent. Decadent plants are more prone to fire. Fire means all that organic matter on the surface either volitalizes in the fire or lays bare to the elements. Now add rain. Nothing can stop the rain from hauling all that yummy organic matter to the ocean or stream. This means the biota of the water now suffers and the upland area are now deprived of their delicious soil. Less can grow. What comes up are things that sprout quickly after a fire and can live on very little soil. Whatever remaining megafauna there are now must struggle to find food. they are weakened by the new settlers as well as the major environmental change caused by the inbalance in the ecosystem. They, except the buffalo, die off.

The remaining life tries to find a new balance in this new environment. However, it takes YEARS for soil to form again - especially in more arid climates. Probably just as this was heading in the right direction, new settlers came and changed things again. Unknowingly throwing off the whole balance again. I have an un-tested theory that if given proper treatment, this land could be much more fruitful than it currently is and ever was in the eyes of the European settlers.

I agree with you, Amit. I think much of the damage could be reversed if people wanted to and used permaculture techniques. Unfortunately in my locale people are still following bad practices such as burning brush. Even after I try to give them a better example, our neighbors just hate brushpiles, so they burn them.

I think this quote is very suitable for this conversation:

"If history repeats itself, and the unexpected always happens, how incapable must Man be of learning from experience."
~George Bernard Shaw

I know the Walnut Creek area near Prescott, AZ was "impenetrable" back when the European settlers came in due to thick cottonwood forest. It no longer is, and many environmentalists blame overgrazing. Might be true. Wonder what Allan Savory would say about it.

The BLM is looking at pioneer era graveyards, protected by fencing, to find samples of native grasses that had been all but wiped out by nearly 100 years of overgrazing in the Great Basin. The early settlers learned quickly about the hazards of overgrazing, but their efforts at land management were often disrupted by "pirate" herds of sheep, often numbering in the hundreds of thousands, that would quickly denude areas that were being rested. This stressing of the land, combined with the introduction of invasive species, particularly cheat grass, has changed forever what was seen in the early 1800's.

What the early Europeans saw in California when they first arrived was the result of generations of land management that maximized what the aboriginal population wanted from it (and humans are not alone among organisms in manipulating the environment for their benefit).

What Spanish explorers saw in the American South in the 1500's was completely different from what later explorers and settlers found in the 1600's through early 1800's. Some attribute this to the massive die-off (70-95%) of native peoples from introduced diseases disrupting their ability to continue managing the land as they had for generations previous.

I am sure that we could make things "better", as we would define it now (a definition that continuously evolves), but I doubt we could restore the environment to what existed before.

Changing climates will also force changes in flora and fauna. Our climate is forever changing, with or without our help, and with or without our permission. What was reported about a region's physiography generations previous is likely not entirely applicable now, and our experience, while perhaps interesting to our descendants a few generations down the road, may not be entirely helpful to them. Fortunately, we are a highly adaptable species and have a long history of making the most of a situation, when we allow ourselves to. I think they will do fine.