This question is related to a picture. In the picture you can see that a small town was affected by a landslide located near a steep hill. As the statement reads, it can be a destructive process as not only is the countryside affected by removal of the top earth layer along with all the vegetation in that area, consequence of heavy rainfall or a mayor earthquake or shift in landmass, but it also turns into a constructive process as at the bottom of the hill, where the landslide or mud accumulates, the debris forms a new layer over the old and it is then seen as constructive.
By measuring the quantity of unstable atoms left in a fossil and comparing it to the quantity of stable daughter atoms in the fossil , scientists can estimate the amount of time that has passed since that fossil formed.