If you spend any amount of time hiking in the Southwest, you will inevitably happen upon a scatter of lovely, multicolored stone flakes lying in the dust. In some areas, obsidian will predominate, and in others yellow jasper, but most often you will see a beautiful mix of red and yellow jasper, various colors of chalcedony and quartzite, light colored cherts, black obsidian and red petrified wood. What you are looking at are the remains of prehistoric tool manufacture.
Native Americans roamed the entire Southwest for at least 12,000 years, and perhaps longer. They were skillful at utilizing the materials at hand, superbly talented at creating flaked implements, and had a love for using the most attractive materials available in the process. One assumes that as they roamed throughout the landscape, they not only went out of their way to visit those places where suitable material was abundant, but also kept an eye out at all times for good quality material when it appeared wherever they went.
The number of lithic scatters (the name used by archaeologists) in the Southwest is in the many tens of thousands, and perhaps millions. Similar scatters exist throughout the country, probably in similar numbers. But only in the Southwest are so many in plain view, because there are so many areas with little or no vegetation, or where plants and trees are separated by areas of bare dirt. If you know where and how to look, finding such scatters is not difficult.
That there are so many such scatters should not be too surprising. After all, Native Americans had no beasts of burden until the re-introduction of the horse by the Spanish. Suitable materials for knapping (fabrication by flaking) typically occur as cobbles the size of your fist or larger, and therefore are too heavy to carry in volume in their raw form. As a result, when a piece of material was found, it would be reduced to much smaller sizes and shapes that could later be turned into atlatl (spear thrower) darts, knives, and (in later times) arrowheads. This not only allowed the heavy core of a cobble to be left behind (the part that could not be further split in such a way as to yield a useful piece of material) along with other unusable bits and pieces, but also meant that cobbles and pieces of cobbles with fatal flaws could be discarded out of hand when the flaws became apparent as they were reduced to smaller sizes.
Consider also that at first hundreds, and eventually millions, of individuals roamed North America over a period of at least 120 centuries. Since all were hunter-gatherers until relatively recent times, this meant that Native Americans rarely stayed in one place for very long, or necessarily returned to exactly the same location in their annual cycle of travel. Each time a band camped, new tools might be made out of the blanks (called performs) that had been shaped at quarry sites, and old tools would need to be repaired or turned into smaller tools when they broke in their original form. If you do the math, you can see that the number of places where flakes would have been deposited would be very large indeed.
I suspect that there was a third factor as well that would have led to even more scatter locations: call it the "knitting effect."
Many times you will find only a handful of small flakes on the ground, with nothing else to indicate that anyone had ever been anywhere else in the immediate area. My supposition is that many who made stone tools worked like those that have knitting as a hobby. That is, in this case, if a Native American stopped for a rest or chatted with friends, out would come his leather pouch of performs and antler tips (for pressure flaking), and he would create a point or two to help while away the time.
The small scatter is one common type of deposit of flakes (or debittage, as rock waste is more properly called). Often you will find large areas, sometimes many acres in size, where a layer of cobbles has become exposed, perhaps on the bottom of a long-evaporated lakebed. In these areas, the ground will be covered with large, multicolored pieces of material, most from one to four inches in length. These are quarry sites, and if you were to look for hours, you would not be likely to find a single completed artifact, because the task at hand was to create pieces of raw material that could be carried away and be turned into any of a variety of tools at a later date.
At other times, you may find a mix of large and medium size flakes. These are reduction flakes: those that were removed from a larger piece to turn it into a preform, or to turn a large perform into a small tool.
Where tiny flakes are found, they mark a place where tools were being finished or repaired. These are pressure flakes, and often indicate the location of a campsite. While small flakes can be created by percussion (i.e., by striking the nearly completed tool with something more forgiving than stone, such as a billet made out of the base of an elk antler), the final edgework of a tool was more often accomplished by pressing small flakes off the edge of the tool using the tip of an antler. If you look at a finely created artifact edge-on, you will see a flat zigzag created as a flake was removed from first one side, and then the other. If you look down on the broad face of the finest and oldest artifacts, you will see that these tiny flake scars form an exquisite pattern that evidences very fine and meticulous work indeed.
Figuring out where to look for quarry and habitation sites, for me, adds an interesting focus to choosing hiking routes. But before you become too interested in taking up arrowhead collecting as a hobby, know that almost all of the Southwest is "catch and release" territory: it’s illegal to keep artifacts found on any federal land, and the same rule applies in state parks as well. If you violate the rules, you may be caught (and not released).
So unless you’re willing to take only pictures of artifacts, and leave them where you found them along with your tracks, it’s best to take up bird watching instead.
Which, by the way, is also great out here.