Lab work can be fun (and archaeology complicated)

I spent a few hours today washing artifacts from a small dig our company just did in Williamson County. I was not a part of the crew (I was in East Texas), so all of the things I'm washing are new to me, and I don't know much about the site in general. It made things very interesting, because I got to look for patterns in the recovered artifacts that might contribute to an understanding of the site, with almost no preconceptions. Some of the things I noticed may prove useful for the report and making a suggestion for further work, which made me pretty damn proud of my archaeo skills.
I also like washing because in some ways it's like a second stage of discovery. When you're dealing with 100s of pieces of dirty chert and a limited amount of time to dig, you WILL miss stuff. So when you're washing all the stuff, you get to find some goodies.
This site, like many Texas sites, is challenging because in a lot of ways it is a palimpsest. There's about 30 centimeters worth of deposits that are full of artifacts, but these represent literally thousands of years of occupation. Generally speaking, the newer stuff is on top of the older stuff (which is the proper context) but there's no obvious strata in order to separate the actual occupations. If you can envision a small landfill, where 3 or 4 houses dumped their trash for several generations, you get the idea. Actually, this analogy works very well because you will also be faced with the archaeological reality that perishable goods (organic material) decay quickly while non-perishables (rock, glass, metal to an extent) remain.
One of the characteristics of this particular palmipsest is that the lithic artifacts are patinated, even though they are currently as deep as 50-60 centimeters below ground surface. When chert is exposed to sunlight for prolonged periods of time (100s of years or more), it's patina can change color or become cloudy or glossy. So when you have 70% of your artifacts that are now 2 feet below the surface patinated, it means that stuff was sitting on an old surface for a very long time, a long time ago.
What's really interesting is that below this level is a much more sparse layer of artifacts, which are not patinated. Furthermore, the matrix is of a slightly different color brown (remember back to the Munsell conversation? This suggests that there's probably an intact, short-term occupation below the palimpsest/goodies level. While one would think that archaeologists are just interested in a bunch of sweet projectile points and tools, what we really like to find at sites are temporally discreet, isolable deposits. Imagine that our landfill is built on the edge of an active floodplain, so that every few months the trash gets covered with a couple of inches of dirt before more trash is dumped on top. This way, each layer of trash captures a short span in the life of a small group of people, but the odds of finding really interesting things are diminished.
In this case, there's no clearly diagnostic tools from this lower level, just a bunch of debitage. On the one hand, having a possible discreet component makes this site worth more work. On the other hand, what was uncovered thus far doesn't suggest that further work would uncover more significant, helpful information, at least within the current right-of-way. Since this is taxpayers' dollars at work, we have to make a compelling argument for further work (which spends more money and delays the project) if we really believe that this site has potential to yield unique and important information. That, ultimately, is the true challenge of CRM archaeology.