It is very difficult assigning a date to a sedimentary rock, especially ones of recent origin. One modern technique is Optical Stimulated Luminescence where doses of ionising radiation are measured in quartz grains and estimates made when those grains were last subjected to sunlight. The geology department of Utah State University explains it concisely:
Optically-Stimulated Luminescence is a late Quaternary dating technique used to date the last time quartz sediment was exposed to light. As sediment is transported by wind, water, or ice, it is exposed to sunlight and zeroed of any previous luminescence signal. Once this sediment is deposited and subsequently buried, it is removed from light and is exposed to low levels of natural radiation in the surrounding sediment. Through geologic time, quartz minerals accumulate a luminescence signal as ionizing radiation excites electrons within parent nuclei in the crystal lattice. A certain percent of the freed electrons become trapped in defects or holes in the crystal lattice of the quartz sand grain (referred to as luminescent centers) and accumulate over time (Aitken, 1998). (Source).
The source of the ionising radiation is the crucial factor, as well as the mechanism of forming the individual quartz (and feldspar) grains.
The concept ‘geologic time’ is vague and imprecise, invariably meaning a very long time, especially if the inferred source of ionising radiation is at the trace levels. However a logical fallacy seems to be operating in this model, that of our old friend of arguing the consequent. That the quartz grains emit light when stimulated in the laboratory is not being questioned, but rather how these grains acquired the property in the first place.
It is almost a geological axiom that quartz grains found in sediments are the result of a prolonged attritional process of transportation either in hydraulic flow regimes, creeks, rivers etc or via the process of saltation as air-borne particles in a sand-dune climate and environment. The mechanism implies small bits of quartz being abraded off the larger crystals as these larger grains are transported over long distances. Given that such a mechanical process winnows out any unstable ir less durable particles, then the ultimate resting place or deposit, will be essentially monomineralic, and comprised of the more resistant mineral phases. Radiogenic nuclides are not generally known to be deposited in such environments since by definition such nuclides are unstable and not able to survive long periods of abrasive transport.
But the luminescence is real and is the result of irradiation. Lacking any alternative evidence, mainstream archaeology and geology assume the irradiating sources have to be present in the source rocks in which the tested grains are sampled from. But this is simply a logical fallacy.
It is more likely that the irradiation of the quartz grains is achieved by a different process. In this process quartz sands are the result of prolonged EM machining, in the electric plasma domain, of in-situ deep regolith material from which innumerable micro Z-pinches form quartz grains of varying size and chemical composition, obviously in trace amounts. Plasma Z-pinches are sources of intense radiation so that quartz grains would reflect this provenance of formation.
Plasma Z-pinches are extremely powerful forces compressing matter into, initially, unstable high density phases that when freed from the Z-Pinch mechanism will then exist as radioactive, and hence unstable, nuclides that then start to transform, slowly, and dependent on the ambient electric field in which they exist, to more stable, less radioactive phases.
The standard model of OSL is based on geological gradualism in which sediments are slowly accumulated over geological time as part of the geological cycle. This model relies on radiogenic phases being deposited synchronously with the quartz grains in the sediment. That most sandstones and shales are not radioactive, is not, it seems, a problem for the mainstream idea of OSL.
The model presented here is that OSL is real but produced by the rapid deposition of detrital material formed by the operation of plasma Z-pinches during a catastrophic climate event in which the Earth’s surface was eroded, transformed into crystalline quartz, and rapidly deposited. The measured luminescence does not come from prolonged burial as a secondary diagenetic process. but as a remnant of a primary process that formed the quartz grains in the first place.