Thus, it affects the disciplines of sedimentology and stratigraphy within geology. Fossils of invertebrates are commonly used in stratigraphy. Archaeological stratification or sequence is the dynamic superimposition of single units of stratigraphy or contexts. Consequently, palaeontologists rely on stratigraphy to date fossils. Most of the Cambrian stratigraphy is based on the use of trilobite marker fossils. Archaeological stratification or sequence is the dynamic superimposition of single units of stratigraphy, or contexts. This has led to the specialized field of isotopic stratigraphy. Geologists also obtain data through stratigraphy, boreholes, core samples, and ice cores. The Late Tithonian is coeval with the Portlandian stage of British stratigraphy. Excavation of this site has resulted in the discovery of four layers of stratigraphy. Little is known about the stratigraphy of the Paleozoic. Some of the most important craters used in lunar stratigraphy formed in this recent epoch. These walls sometimes expose layers that represent the glacier's stratigraphy. His thesis treated the mammals of the French lower Eocene and their stratigraphy. Further analysis of the stratigraphy and artefacts from the site was carried out.