We're on an annual working sabbatical every summer from July 1st through September 1st and the XRF lab is semi-closed during that period for field work, instrument and computer maintenance, and website updating. We maintain an active summer field work program and are often out of the lab chasing down new obsidian sources during this period. We're also sitting on an impressive pile of data and information and this will also give us some extra time in which to compile, organize, and synthesize it for you.

If you've got questions or pressing projects or emergencies that are due during the summer, don't worry - we'll be checking in on a regular basis and won't leave you late or hanging. Please let us know in advance as far as possible and we'll make sure that your projects get done on time.

Above: In the picture above, we're standing atop Vulcan's Thone, an 800 ft-high Pleistocene cinder cone on the North Rim of the Grand Canyon in northern Arizona. Click on the picture above or HERE for more details - you'll need Java enabled to look at some of the images. Ever since we began running into obsidian artifacts to the north of the canyon that originated from obsidian sources on the south side of the Grand Canyon, we've been thinking hard about the influence of geographic barriers to the movement of artifacts and wanted to see for ourselves just what kind of a barrier the canyon might be. A formidable one, to be sure, but apparently still porous. Toroweap Point can be seen near the lefthand edge of the image.

Above: Bodie Hills, California - a view west down Aurora Canyon and a close look at the glass nodules and flakes that litter the ground in this area. On the way south to the North Rim, we visited several archaeologically-significant obsidian sources along the east side of the Sierra Nevada Range - Sutro Springs, Bodie Hills, and Mono Craters. Obsidian from these Bridgeport area sources is widely distributed at sites along the eastern margin of the Sierras and is also found in surprisingly large quantities at sites in central California and along the central California Coast, the result of a very active trans-Sierran obsidian procurement and exchange system.

Below: Mono Craters, California - Mono Lake is in the foreground. The late Holocene (13th century A.D.) volcanic activity that produced Mono Craters created a 10 mile-long chain of obsidian domes and flows (including two islands in Mono Lake). Unlike the more widely-distributed obsidian from other nearby sources - Casa Diablo, Bodie Hills, Mono Glass Mountain, and Mt. Hicks (NV) - artifacts manufactured from Mono Craters obsidian are largely restricted to the immediate region around the local Mono Basin.

Above: We're back from a fast foray to the South Sister Volcano and Broken Top area of Oregon's central High Cascades where we were looking at the distribution of obsidian from Tumalo Creek. This is an obscure and poorly-known source of glass located on the eastern slopes of Broken Top and one that only rarely shows up in the archaeological record. In the photo above taken looking north from Sparks Lake, South Sister Volcano is in the background - a 2,000 yr-old chain of poor-quality obsidian domes stretches south towards the lake. The pictograph that serves as the lab logo was copied from rock art found on the southernmost of these domes.

Below: A view of Obsidian Cliffs, one of Oregon's most archaeologically-significant sources of obsidian, looking southeast from across Lost Creek Canyon. We had intended to spent a couple of days at the source but plans were derailed by an unexpected road closure in 2007 (we'll be back in 2008). Instead we ended up looking for nodules of obsidian in glacial moraines - the source was overriden by glaciers in the late Pleistocene and chunks of glass were transported westward into the McKenzie River drainage (and from there eventually into the Willamette Valley). The prominent cliffs near the center of the image below mark the western terminus of the obsidian-rhyolite flow. The Little Brother and Middle Sister loom in the background.

Above: The view of Newberry Caldera from the summit of Paulina Peak - it was an unusually clear day just prior to the outbreak of several large fires in eastern Oregon. The 1,350 year-old Big Obsidian Flow is located on the righthand side of the panorama. Also within the field of view are several other archaeologically-significant post-Mazama flows of obsidian, most of which share the same trace element signature, the Newberry Volcano source group. Although we've had samples from the caldera obsidian flows in the lab source reference database for many years, we recently managed to relocate a Newberry Volcano source flow that lies outside the boundaries of the caldera on the southeast flanks of the volcano. The unit is thickly mantled by tephra deposits and was found by chance in the mid-1980's during a visit to the very obscure Little Obsidian Flow. That small post-Mazama flow is covered by tephra from the eruptions at the Big Obsidian Flow vent but does not appear to be a source of any artifact-quality glass.

While we were in the area in 2006, we had another quick and unproductive look for the elusive Unknown X obsidian source that we suspect is located somewhere within a few miles of the McKay Butte source. The Unknown X obsidian, a popular pre-Mazama toolstone source, was first identified in 1991 from provenance studies carried out during the extensive PGT-PG&E Pipeline Expansion Project that ran immediately west of Newberry Volcano. Guided by geologic mapping of Newberry Volcano, we have a checklist of possible source localities to look over in 2008.

Below: Vent Cave, one of several small severely-disturbed (by pothunters) lava tubes located on the northern side of Newberry Volcano in the Lava Top Butte vicinity. We've been meaning to wrap up some long postponed obsidian provenance research at these caves (two of which are perennial water sources) and will have a last look at the caves over the summer of 2008 (if we can find them all again).

Above: Once again, we're back at Glass Buttes ... here's the view looking north from the eastern end of the Glass Buttes source complex (June 2006). The massive outcrops of obsidian at Glass Buttes have been a lab research priority for the last several years and we continue to add more sampling locations whenever we're in the area. So far, we've identified nine geochemically-unique sources of obsidian at the complex and in secondary deposits in the basins to the north and south of the main source area. At this point, it seems likely that we won't find any new sources but there's still a lot to learn about the boundaries of availability for the different sources. We'll be following up on that angle once again in 2008.

Below: Looking north from Wagontire Mountain across the Sinks of Lost Creek basin towards the south side of the Glass Buttes Source Complex. Secondary deposits of glass from several of the Glass Buttes geochemical varieties are common in the basin to the south of the source complex.

Above: Left - Here's the classic view of Fort Rock, a spectacular Pleistocene tuff ring located in the Fort Rock Basin of Oregon. The landform once stood as an island in the late Pleistocene Pluvial Fort Rock Lake but was high and dry by the time the area was inhabited. Right - The well-known Fort Rock Cave is visible in the middle distance from the top of Fort Rock.

Below: Looking north towards Cougar Mountain, the most significant source of natural glass to the prehistoric inhabitants of the area. In 2006, we began a systematic survey of area gravel pits and other lacustrine deposits in order to better understand the widespread natural distribution of obsidian nodules that originated from Cougar Mountain. We'll be back again to finish up in 2008.

Above: A perennial tank of water located in a fault-controlled intermittent stream drainage in the Wagontire vicinity. Obsidian from two different sources, Tank Creek and Big Stick, was identified among the glass nodules collected from fluvial deposits at this location. Another nearby natural tank awaits a 2008 visit. Wagontire Mountain lies in the distance.

The region from the Wagontire Mountain area east to the Harney-Malheur Basin has proven to be a vertitable treasure trove of poorly-known and prehistorically-significant obsidian sources. These range from geographically constrained sources (e.g., Bald Butte and China Lake) to those that have been naturally distributed downlope through complex drainage systems (e.g., Wagontire Mountain, Tank Creek, and Big Stick) to those that are associated with massive eruptions of volcanic ashflow tuffs that cover large geographic areas (e.g., Buck Springs). We think that we've now located most of the extant unique geochemical obsidian sources in the region and are focusing on understanding their natural geographic distribution.

Below: Hidden away on the northern slopes of Wagontire Mountain are a series of springs and the perennial (but short) Lost Creek. Although the area has been thoroughly disturbed by generations of cattle grazing, evidence of the prehistoric use of the springs is abundant in the form of obsidian flakes from Glass Buttes and other sources to the east. Glass Buttes can be seen in the far distance peeking above the end of the valley.

Above and Below: We're still not done scouting out the Dry Creek drainage for nodules of obsidian from several geographically widespread sources bordering the stream. The glass has been transported down this drainage as far east as the Owyhee River. We have yet to get to the remote Dry Creek Gorge in the central portion of the drainage but plan to in 2008.

Above: A view east from the Quinn River towards the Santa Rosa Mountains of northern Nevada. The archaeological site at this spot is located only a few miles southeast from the Double H Mountains obsidian source and small nodules of culturally-unmodified glass from the Double H source are common in the river terrace deposits. Working in conjunction with Craig Young and Steve Neidig (Far Western Anthropological Research Group), we're in the midst of a thorough look at the geochemistry of the Double H obsidian source and a sampling of archaeological sites near the source. Initial indications are that the source is geochemically quite variable and covers a much larger than anticipated geographic area. The final report is now completed and is due out sometime in 2008.