Radioactive isotope dating techniques are usually used for sedimentary rocks
{"Image DocumentName": "Radiometric dating is used to estimate the age of some rocks", "Image ImageDescription": "There are THREE basic rock types: IGNEOUS. [cooled from molten rock] SEDIMENTARY. [mixed particles of igneous rock] METAMORPHIC. [reheated sedimentary rock] Only igneous and metamorphic rocks can be used for radiometric dating as the radioactive materials are frozen in when the rock cools. BUT\u2026 the vast majority of fossils are found in sedimentary rock layers. About 75% of the Earth\u2019s land surface is covered by sedimentary rock. Therefore, fossils cannot normally be dated using the rocks in which they are buried \u2013 only adjacent strata where applicable.", "Image XResolution": "300", "Image YResolution": "300", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}