Page 25 - Atlas of Creation Volume 1

Harun Yahya

During these studies, it was observed that specific fossil species were found only in specific strata
and certain types of rock. Consecutive rock strata were observed to contain their own fossil groups,
which could be regarded as that particular layer's "signature." These "signature fossils" could vary,
according to time, period, and area. For example, two different environmental conditions and kinds of

sediments—an ancient lake bed and a coral reef, for example—might be encountered in the same fossil-
bearing stratum belonging to the same geologic period. Alternatively, one might encounter the same
fossil "signature" in two different rock beds many kilometers apart from one another. Through the

information imparted by these remains, scientists determined the geological time frame that we still use
today.

Fossils used to determine the formation dates of rocks are
Pictured are a trilobite that lived in the called index fossils. The majority of these species
Ordovician period (490 to 443 million are ones that lived in only a particular period,
years ago) and a gastropod from the that were widespread and easily
Silurian period (443 to 417 million recognizable.
years ago). From these fossils, we can
guess that the rocks in question are
around 448 to 442 million years old.

Adnan Oktar 23