Surface exposure dating with cosmogenic nuclides things to do dating website
This is because the cosmic rays, which bombard Earth at a more or less equal rate from all sectors of the sky, will be reduced if the view of the sky is shielded — for example, by a large mountain that the rays cannot penetrate.
Scientists must therefore carefully measure the horizon line all for degrees all around their boulder.
Trimlines can therefore also be used to reconstruct past ice sheet thickness.
However, this can be difficult, as thermal boundaries within the ice sheet may mean that it is more erosive lower down than higher up, and that cold, non-erosive ice on the tops of mountains may leave in tact older landscapes.
Many mountains have trimlines on them, and are smoothed and eroded below the trimline, and more weathered with more evidence of periglaciation above the trimline.One of the largest errors in cosmogenic nuclide dating comes from a poor sampling strategy.Because cosmic rays only penetrate the upper few centimetres of a rock, movement of a boulder downslope can result in large errors in the age calculated.For a rock to be suitable for cosmogenic nuclide dating, quartz must occur in the rock in sufficient quantities and in the sufficient size fraction.A general rule of thumb is that you should be able to see the quartz crystals with the naked eye.