Another absolute dating method is thermoluminescence, which dates the last time an item was heated. Principle of Inclusions, inclusions in a rock are older than the rock layer itself. Angular unconformity an unconformity below which older rocks dip at a different angle (usually steeper) than overlying strata. Fossil assemblages frequently used for identification of a disconformity. Archaeologists are seeking an accurate dating technique, but this method is yet to be found. When the meltwater reaches a lake the heaiest sediments (sand and silt) sink to the bottom quickly and eventually formed thick layers of light colored rock. . All methods can be classified into two basic categories: a relative dating methods : Based on a discipline of geology called stratigraphy, rock layers are used to decipher the sequence of historical geological events. Beta decay electron emitted from a neutron, which changes to a proton; atomic number increases by. Related Books, related Videos.