Relative dating interactive
In the past 150 years they have not found any fossils that Darwin would not have expected.
Today, innovative techniques provide further confirmation and understanding of the history of life.
Biologists actually have at their disposal several independent ways of looking at the history of life - not only from the order of fossils in the rocks, but also through phylogenetic trees. Relative dating is done by observing fossils, as described above, and recording which fossil is younger, which is older.
Since then, geologists have made many tens of thousands of radiometric age determinations, and they have refined the earlier estimates.
A key point is that it is no longer necessary simply to accept one chemical determination of a rock’s age.
By doing this, you will unravel the geologic history recorded in the rock record, just as geologists did hundreds of years ago, and still do today. An earlier current-formed ripple set (at bottom of slide) was later modified by a second ripple train migrating at right angles to the first.
Crests of the first set are preserved in the troughs of the second set, hence, the ladderback appearance.Darwin and his contemporaries could never have imagined the improvements in resolution of stratigraphy that have come since 1859, nor guessed what fossils were to be found in the southern continents, nor predicted the huge increase in the number of amateur and professional paleontologists worldwide.All these labors have not led to a single unexpected finding such as a human fossil from the time of the dinosaurs, or a Jurassic dinosaur in the same rocks as Silurian trilobites.The fossil record is fundamental to an understanding of evolution.Fossils document the order of appearance of groups and they tell us about some of the amazing plants and animals that died out long ago.Overall we had another successful day of stations with smooth transitions!