SITES IN CALIFORNIA HAVE BEEN DATED USING A SCIENTIFIC TECHNIQUE CALLED OBSIDIAN HYDRATION WHICH WAS DISCOVERED BY IRVING FREIDMAN IN 1960. IN ORDER TO DATE OBSIDIAN A DIAMOND SAW IS USED TO MAKE A SMALL CUT FROM A TOOL OR FLAKE THAT IS TO BE DATED. THE PIECE IS PUT UNDER A MICROSCOPE AND THERE IT IS SEEN AS A CERTAIN THICKNESS OF HYDRATION. IT IS MEASURED MEASURED IN MICRONS AND A CELEBRATION HAS BEEN REFINED SINCE THE 1960'S. DIFFERENT OBSIDIANS ABSORB WATER AT DIFFERENT RATES. FACTORS THAT DETERMINE THE OBSIDIANS RATE OF HYDRATION INCLUDE TIME AS WELL AS THE TEMPERATURE OF THE OBJECT AND CHEMICAL.
ABOUT 20 OBSIDIAN QUARRIES HAVE BEEN FOUND IN CALIFORNIA. THERE PROBABLY ARE EVEN MORE QUARRIES. OBSIDIAN WAS THE PREFERRED MATERIAL AS IT IS EASIEST TO KNAP OR FLAKE OFF CHIPS FOR PROJECTILE POINTS AND ALL OTHER NECESSARY TOOLS NEEDED FOR PLANT PROCESSING AND ANIMAL HUNTING AND PROCESSING. IT IS THE EASIEST MATERIAL TO KNAP OR FLAKE OFF CHIPS FOR PROJECTILE POINTS. I HAVE TAKEN CLASSES IN KNAPPING OBSIDIAN AND FOUND IT VERY FUN.
MOST NATIVE AMERICANS FOUND THIS ROCK AS SPIRITUAL AS IT WAS MOLTEN GLASS FROM VOLCANIC EXPLOSIONS THOUSANDS OF YEARS AGO.
SOME OF THE TOOLS ARCHAEOLOGISTS FIND ARE: KNIVES, SCRAPERS, PLATFORM CORES, CHOPPERS, BIFACES, SHELL BEAD DRILLS, BONE SHARPENERS, CHOPPERS, BIFACES, SCRAPPERS FOR WILLOW AND OTHER BRANCHES USED FOR STRUCTURES AND BASKETS. THE PARENT ROCK IS CALLED THE CORE AND IT HAS CORTEX ON THE OUTSIDE. IT IS STRUCK BY ANOTHER HARD ROCK IN ORDER TO PRODUCE SMALLER FLAKES TO USE OR WORK INTO TOOLS. FLINT, JASPAR, CHERT, CHALCEDONY, BONE, AND QUARTZ WERE SOME OF THE STONES KNAPPED FOR TOOLS. EXPERIENCED KNAPPERS USE DIRECT PERCUSSION AND PRESSURE FLAKING TO FINELY SHAPE POINTS AND SCRAPERS. THEY USE ANTLERS AND BONE TOOLS FOR PRESSURE FLAKING. ISHI WAS STUDIED AT BERKELEY AND THEY NOTED HOW CAREFULLY HE KNAPPED AND PRESSURE FLAKED A PROJECTILE POINT USING AN AWL MADE OUT OF BONE. STONES WERE ALSO HEATED IN FIRE AND COOLED WITH WATER TO MAKE SHARP TOOLS EASIER.
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