Rock varnish microlamination dating absolutely worldwide dating sites
Scanning electron microscopy with X-ray microprobe analysis indicates that the major elements composing these films are O, C, Si, Al, Fe, Ca, Mg, and S.
It is shown that the films of the rock varnish and the organomineral films in the fissured zone of the rock under the plate with endolithic communities have certain similarity in their morphology and composition: the films of the rock varnish also contain biota (dead cells or cells in the dormant state), and their botryoidal structure is similar to the structure of the biofilms inside the endolithic system.
The close agreement between the VML age estimates and the independently derived radiometric ages for these geomorphic features attests to the validity and reliability of millennial-scale VML dating.
To further assess its potential in desert geomorphological research, we use the VML method to study alluvial-fan responses to millennial-scale climatic changes.
These data indicate that, on the millennial to sub-Milankovitch timescale (~10³–104 years), fan aggradation is a discrete sedimentational process under various climatic conditions.Although the origin and meaning of the art vary regionally, it apparently resulted everywhere from ritual practices—it was a product of shamanistic religions in the hunter-gatherer Far West, for example, and was intended to depict visionary experiences.Depending upon tribe and context, it was made by puberty initiates during group or individual ceremonies, by shamans on solitary vision quests, and/or by nonshaman adults during life crises.While these improvements are cause for optimism, serious problems persist. The United States has a particularly rich record of rock art.For example, there are about fifteen hundred registered sites in California alone, with equivalent or greater numbers in other western states.