by Richard L. Thornton, Architect & City Planner
This week I have discovered that ultra-violet light causes man-made topsoil or terra preta to look entirely different than natural soil, even to the naked eye. As you will see in my research report next week, under the 1000x (3D) and 1200x (2D) magnification of my two digital microscopes, soil contents look starkly different. Ultraviolet also dramatically affects the magnified appearance of petroglyphs, Native American pottery AND many rocks.
I strongly recommend to all of you, who go out in the field looking for vestiges of past occupants in the Americas, purchase an ultraviolet flashlight. They are as cheap as $9. I purchased a high-powered one that is rechargeable, for $19 on Amazon.com.