Before this, archaeologists and scientists relied on deductive dating methods, such as comparing rock strata formations in different regions.Chronometric dating has advanced since the 1970s, allowing far more accurate dating of specimens.In the Southwest, and particularly in CRM, there are several defined types of survey: Remote Sensing: Remote sensing in archeology employs a wide variety of aerial and satellite imaging, as well as radar, sonar and lidar, to build landscape images useful for recognizing archeological materials not visible to ground crews.Many remote sensing techniques rely on portions of the electromagnetic spectrum, such as infrared, that humans are typically unable to see.Survey: Survey accounts for the initial in-field investigations of a region, and aims to record artifacts, features, and site locations of archeological interest.
But, even when the scientific methods of absolute dating are available, this method of dating has not lost its importance, as many a time we have to depend solely on relative dating.
The deposit thus occurring forms layers depending on the nature of the material brought in by the people inhabiting the area.
According to this method, the upper deposits are younger and the lower deposits are older.
Some scientists prefer the terms chronometric or calendar dating, as use of the word "absolute" implies an unwarranted certainty of accuracy.
Absolute dating provides a numerical age or range in contrast with relative dating which places events in order without any measure of the age between events.