Relative dating of fossils is based on what Cyber sexchat bot
There are some radioactive elements in rock that decay by giving off energy and turning into different, more stable elements.
This radioactive decay takes place at a constant rate for each radioactive element.
The sediment of this area was laid down after ammonite A appeared 199 million years ago, and before ammonite B became extinct 195 million years ago.
This narrows the date of the delta beds to the four million years between these dates.
The lava flow took place some time after the diorite cooled, was uplifted, and then eroded.
The best examples are fossils of animals or plants that lived for a very short period of time and were found in a lot of places.
Ammonites, shelled relatives of today’s octopus, make ideal index fossils.
Suppose a dinosaur fossil has been found in the beds of an ancient delta (the mouth of a river leading to the sea).
The simplest and most intuitive way of dating geological features is to look at the relationships between them.
There are a few simple rules for doing this, some of which we’ve already looked at in Chapter 6.
The Age of Dinosaurs was so many millions of years ago that it is very difficult to date exactly.