Dating exposed surface contexts
Tuniz (eds), Advances in dating Australian rock-markings, pp. Occasional AURA Publication 10, Australian Rock Art Research Association, Melbourne. Ambiguities in direct dating of rock surfaces using radiocarbon measurements; with response by R. The age range of luminescence dating extends from modern samples ( years, thus covering all periods of known human occupation of Scotland, and much of the Palaeolithic elsewhere.Precision of dating varies from sample to sample, and from context to context, depending on individual sample characteristics (mineralogy, luminescence sensitivity, stability and homogeneity of the radiation environment, and the quality of initial zeroing).The “dose rate”, measured in m Gy/a, is determined by combining field and laboratory analyses of the levels of naturally occurring radionuclides and cosmic radiation with an appropriate microdosimetric model for the mineral phase in question.
You may notice that in front of one house the snow is deep, while next door the sidewalk may be almost clear. More likely, you conclude that Jones has recently swept the walk clean and Smith has not.Note that the age of these surfaces is not necessarily the age of the planet as a whole.On geologically active objects (including Earth), vast outpourings of molten rock or the erosive effects of water and ice, which we call planet weathering, have erased evidence of earlier epochs and present us with only a relatively young surface for investigation. This technique works because the rate at which impacts have occurred in the solar system has been roughly constant for several billion years.The answer to that question is: 48 to 108 million years. I just wrote two long blog entries about relative age dates on Mars derived from crater counting and from stratigraphy and spectroscopy.I explained in an earlier post how difficult it is to put actual numbers on these relative time scales, even for Earth, and I didn't even bother showing you absolute time scales on Mars. How do these age dates fit in with what I've told you about Mars' history?