Rock layers are the pages of the book where the History of the Earth is written How far can this analogy be stretched?

Category Other
Group GSI.IR
Location International Geological Congress,oslo 2008
Author Sellés-Martیnez, José
Holding Date 11 October 2008

The first statement in the title is a common place, used in many Geology introductory books. It clearly illustrates that the information about the past of our planet can only be found in the rocks. Rocks and -in a wider sense- all geologic materials, allow us to extract information out of them. This information, relevant to the identification of processes active in the past, can be looked for in their shapes, textures, structures and composition. Important indeed is that information about past times of the Atmosphere, Hydrosphere and Biosphere can only be deduced from evidences and proxies left in the Geological record. This is especially relevant today for the study of Global Change, for example.
Comparing rocks with a book and Geology with the language it has been written, as usually done, is a good analogy although it refers more to a synthesis of the Earth’s History than to details here and there along the record. Something like a Universal History book in which information from different sources has been analyzed, selected, discarded, etc., suffering all those operations the author has found necessary to carry on in order to accomplish the task of reducing a huge amount of information to a regular book. This limitation can be tackled If the analogy is made using collections of journals and the comparison broadens largely and offers a lot of new relationships to be found and discussed.
On the one side, processes and influences ranging from local to global, can all be found recorded in each rock column and represented in geological maps at different scales. This is so for concepts ranging from the Principle of Superposition to palaeogeography; from unconformities to palaeoclimates and from water currents direction to the evolution of life. On the other, most relevant features of a journal -like format, periodicity, area of influence, thematic sections, services, etc.- help the scholar in his search for information and historical and/or geographical reconstruction of the facts and processes in the past. These presentation- and contain-related features in newspapers and journals are analyzed and linked to the information stored in the layers that build up the geological column of any area on earth.
Care is taken of those elements that can not be compared, or that can lead to wrong analogies; which are underlined in order to prevent misconceptions. The reasons why the proposed analogy is possible and what that means in terms of historical-observational sciences, such as Geology, is briefly discussed.