to: MICRO-DRILL HEAVEN
A short video on Larry's water-screening method.
Here's the set-up, for water-screening micro-drills and fragments, at our lab. The bags are suspended from a rope> water is sprayed into the samples, and the dirt and water fall into the barrel. When the first barrel is full the water flows into the second, third, and fourth barrels. By the time it gets to the fourth barrel (blue barrel), it is clarified enough to recirculate. The recirculation is done with a small sump-pump. It pumps the water, in the fourth barrel, back to the sample. The water is used over and over until it gets full of silt.
We start with half of a 5-gallon bucket of soil. The sample is placed in the middle of the fiberglass screen, and the ends of the screen are folded together to form a bag. Then, the bag is gathered together so no material can escape, and the rope is attached around the bags mouth. Next, the bag is cinched, with the rope. Now, a half-hitch is added, to cinch the knot tighter so no material can leak out.
Then, baking soda is added to about 1/3 bucket of hot water..... ...and the sample is placed in the bucket to soak... ...for about 1/2 hour, or so. I soakk four separate samples so I can work on one while the rest are still soaking After soaking, the bag is fastened to an over-hanging rope with a simople wooden stave. This is done so the samples can be removed and/or readjusted without having to untie any knots. The valve for the main tank is closed and spraying begins. When the main tank becomes too full of silt,... ...the valve is opened and the... ...soil empties... ...onto an area, adjacent to the tank...Next, the tank is washed. All soil is saved and will be used to back-fill the original excavation from which it came. Then, the samples are removed from the screen... ...poured onto a porous cloth... ...the cloth is gathered ... ...then, tied... ... and placed into another bath of baking soda and hot water. After soaking for bout 1/2 hour, the sample is sprayed again to remove all lingering soil, then hung up to dry.
After about two weeks, the samples are ready to be picked. I usually pick about 1/2 scoop at a time. A magnifier is used to.... ...spot the tiny bits of chert. Then, the chert pieces are removed to a plastic box, then, a plastic bag, for later analysis.
Here's what the samples look like after I picked all the chert.
#1 #1 close-up #2 #2 close-up
#3 #3 close-up #4 #4 close-up, #1 #4 close-up #2
Weighing the samples. Micro-drills from North 290-East 135