Early Pleistocene to latest Pliocene surficial deposits
Coarse relict alluvial fan deposits that form rounded ridges or flat, isolated surfaces that are moderately to deeply incised by streams. These deposits are generally topographically high and have undergone substantial erosion. Deposits are moderately to strongly consolidated, and commonly contain coarser grained sediment than younger deposits in the same area. (0.75-3 Ma)
|This is a photo of the aluvial fan sediment that the artifacts are eroding form.|
The photos look great.
This is a conglomerate that overlies Proterozoic rocks in the Phoenix area. A similar unit forms the head of Camelback Mtn and the Papago Buttes and is generally referred to as the Camelshead Formation. The Cenozoic history of central Arizona is very complex and the ages of those conglomerates varies across the Phoenix area. Near the Superstitions, I believe it is as old as 60 Ma (millions of years ago) and would be Paleocene or Eocene. Other places it is Oligocene or Miocene (33-6 Ma). In your top photos I can see the clasts derived from the Proterozoic basement but some of the other photos have volcanic clasts, probably Miocene in age. The conglomerates are too well consolidated to likely be Pleistocene, but their clasts were likely the source of the artifacts.
Good luck in your studies,
These are extremely interesting artifacts and the context is very interesting too. I am not an expert in Arizona desert geology, but the the deposit looks like a cemented debris flow or perhaps a lake-margin deposit. It could very well be Pleistocene in age. It should certainly be possible to date that context if you can get a knowledgeable regional geologist to look it over; for instance by a technique like Infrared Stimulated Optical Luminescence on the sand grains I can see in the surround matrix).
Good luck! Sincerely yours, Curtis
Curtis Runnels, MA, PhD, FSA Professor of Archaeology Archaeology Department Boston University
675 Commonwealth Avenue
Boston MA 02215
Editor, Journal of Field Archaeology
The images of artifacts on this site have been collected form "Private Lands" one is the community I live in which was developed in the early sixties and the other is my Friends property adjacent to the community I live and work in.
The images of the context on this site and any artifacts in the context are "In Situ" on public land. Location will not be disclosed for fear of the looting and or distinction of our National Heritage! And any artifacts within Images of the context are in there original state.
It is also illegal to remove anything from Public Lands with out permission form Federal or Sate Agencies without permit.
ArchaeologyIn archaeology, in situ refers to an artifact that has not been moved from its original place of deposition. In other words, it is stationary, meaning "still." An artifact being in situ is critical to the interpretation of that artifact and, consequently, of the culture which formed it. Once an artifact's 'find-site' has been recorded, the artifact can then be moved for conservation, further interpretation and display. An artifact that is not discovered in situ is considered out of context and as not providing an accurate picture of the associated culture. However, the out of context artifact can provide scientists with an example of types and locations of in situ artifacts yet to be discovered.
The label In situ indicates only that the object has not been "newly" moved. Thus, an archaeological in-situ-find may be an object that was historically looted from another place, an item of "booty" of a past war, a traded item, or otherwise of foreign origin. Consequently, the in situ find site may still not reveal its provenance, but with further detective work may help uncover links that otherwise would remain unknown. It is also possible for archaeological layers to be reworked on purpose or by accident (by humans, natural forces or animals). For example, in a "tell-tell mound", where layers are not typically uniform or horizontal, or in land cleared or tilled for farming.
Sent: Fri, Aug 22, 2014 02:06 PM
I have just calculated dates for 2 small samples taken from the carbonate coating on the worked face of sample AG553b that Curtis sent. The samples yield U-series dates of about 38 and 40 ka! The carbonate is somewhat impure, and the dates required corrections of 6-8 ka due to the impurities. Nonetheless, I think the dates are accurate within a few thousand years.
Berkeley Geochronology Center
2455 Ridge Rd.
Berkeley, CA 94709