Stones, where did they come from?

Posted on July 5, 2012 by Administrator

I am a theorist, not a trained geologist. My intuition tells me that the particles making up the sharpening stones called Awasedo were composed during an extension of short but intense volcanic eruptions of tephra. During this time, millions if not tens of millions of tons of material were released into the air only to settle and cool in pools of fresh water in and around the area where we now call Lake Biwa. And during that period, spurts of iron-rich alternate ash deposits were intermittently carried up into the atmosphere by those same prevailing winds from the volcanic source, and these settled upon the silica and alumina tephra, creating distinct sedimentary layers. The ratio, the particle size, and the distance from the volcanic source were wholly dependent upon specific gravity and the wind. Layer upon layer alighted upon pools of fresh water and settled in an orderly manner. Some tephra layers with chemical components would react to form miniature gas bubbles. Some layers were more variegated, as in these examples,

At intervals determined by the activity of the volcano, massive waves of larger alternate material in particle form and size were thrown farther up, or high enough towards those pools where they settled upon each of the previous deposits. This new material sealed or acted as a cap or shield to partition off the previous layers, thereby retaining the purity of the earlier sediment composition from contaminants. We know this dark-rough particle type in its current form as kawa.

The kawa on each stone is like a fingerprint with unique characteristics of color and chemical composition. The kawa from each mine in the Yamashirio area of Kyoto looks like rough tree bark. Settling like a different locations with sealing its unique chemical composition. In this open-air dispersal scenario, all of the minerals were governed by the specific gravity and wind speed and acted in the same pools as the purer silica material in its dispersal at different distances along the path leading away from the volcano; not randomly, but understandably and logically. It is not difficult to believe that a strong prevailing wind could remain stable in a particular direction for a long enough to deposit large amounts of material.

The commonly held alternate dispersal and layering scenario espoused is that the Awasedo material is radiolarian chert that settled upon the ocean floor, and that all of this activity occurred about 225 million years ago during the Jurassic Era. There is a theme provided by Kyoto University Professor

In either case I hope that this short description will open up some conversations on the subject.

Alx