basalt cobbles, the favored material for making stone tools during the Paleoindian and Early Archaic periods. Chipping stations such as the one below mark ...
Archaeological Lithic Landscapes of the Fort Irwin National Training Center Jeffrey A. Homburg, Steven D. Shelley, Mark Q. Sutton, and Matthew L. Hyland Native Americans occupied the landscapes of Fort Irwin in the eastern Mojave Desert for millennia prior to the of the military training activity. Basalt, chert, quartzite, and other lithic materials are abundant at Fort Irwin. Human populations took advantage of these rocks in the past to make tools such as spear and arrow points, knives, drills, and grinding implements. Stone artifacts are the most common and enduring archaeological trace in the Mojave Desert. These artifacts enable archaeologists to reconstruct: (1) where people lived and obtained resources; (2) a range of ancient human activities such as hunting and plant processing; and (3) how lithic technology and procurement evolved over time. An archaeological survey in support of Fort Irwin’s training mission is now underway in three parts of Fort Irwin. This poster illustrates some of the findings of this field research to document spatial variability in lithic resource availability and use.
LeachLake
Avawatz Mountains Granite Mountains
Drinkwater Lake
Preliminary Findings of the 10K Survey
McLean Lake
No Name Lake
Nelson Lake
West view of edge of Nelson Lake next to the West survey block. Nelson Lake is a pluvial lake where prehistoric settlements are concentrated. Ancient lakes such as this served as important water sources during the moister late Pleistocene and early Holocene climates of the Mojave Desert.
Goldstone Lake
Drainageways such as the one above served as important transportation corridors for humans and game between land in the East block and the next basin to the northeast. Chert is abundant on Pleistocene alluvial fan surfaces in this survey block, as indicated by thousands of chipping stations (see example below) spread across the ancient lithic landscape.
West East Central Bicycle Lake Tiefort Mountains
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Red Pass Lake
Superior Lake
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East view of the Central survey block. Darkcolored rock pavements in the southern half of this block contain abundant fine-grained basalt cobbles, the favored material for making stone tools during the Paleoindian and Early Archaic periods. Chipping stations such as the one below mark places where cobbles were flaked to make bifaces and other kinds of tools.
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Projectile point styles found at Fort Irwin are shown to the right. Spear points are larger and older and arrow points are smaller and postdate ~AD 600.
The West, Central, and East Blocks outlined in red show where the 10,000acre archaeological survey is being conducted.
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Archaeologists documenting a site and recording its location of a site using a GPS (global position system) device (above). Rock art was made by pecking designs on large rock faces. These rock panels mark places of ritual significance at Fort Irwin (below). As manganese oxide and other materials are fixed by microbial processes, dark-colored rock varnish forms on the top of rocks exposed on Pleistocene desert pavement surfaces. Red and yellow iron oxides such as hematite and goethite form where the bottoms of cobbles are in contact with soil and water. The Potable bottom of older basalt cobbles are redder than water was younger ones and older chert cobbles shift from the most yellowish to redder colors over time. Archaeologists limiting aim to determine how these color changes can be resource in used to estimate the age of sites that lack timethe desert. sensitive artifacts such as projectile points. This Springs are study involves documenting Munsell colors on the an important flaked surfaces of artifacts embedded in the ground water source in comparison to natural rocks that serve as controls. for humans The example to the right shows red (10R 5/8) and animals. rubification on a bifacial core (scale = 10 cm).
Lithic resource availability varies across Fort Irwin. The West block is dominated by large basalt cobbles, the Central block by smaller basalt cobbles, and the East block by chert cobbles. Due to its widespread availability, high quality, and durability, fine-grained basalt was preferred by Paleoindian and Archaic populations for making spear points. Chert was used throughout prehistory, but its use intensified in late prehistory. Rubefication (reddening of rocks over time) shows promise for dating archaeological sites on desert pavements that lack temporally diagnostic lithic artifacts.
5 cm Examples of a basalt Mojave point (left, 7500-3500 BC); chert Elko point (upper right, 1300 BC-AD 600), and scraper (lower right).
Acknowledgements Chert chipping stations (green dots) are strongly associated with the dissected, darkcolored Pleistocene desert pavement. Isolated artifacts (red crosses) consist mainly of single cores and flakes that are more broadly distributed on both the Pleistocene and lightcolored Holocene alluvial fan surfaces.
This study is funded by the Fort Irwin National Training Center. (Steve will complete this section to thank Army and SRI personnel.)
