The geological column, also known as the geologic column, is a fundamental concept in geology that represents the organization and relative timing of Earth's rock layers, strata, and the history of Earth's geological events. It is a visual representation of the Earth's history, displaying the sequence of rock formations, fossils, and events that have shaped the planet.
The geological column is divided into different units called "geological periods" or "geological epochs," each representing a distinct interval of time in Earth's history. These periods are defined based on the types of fossils found in the rocks and the overall characteristics of the sedimentary layers. The geological periods are arranged in chronological order, from the oldest at the bottom to the youngest at the top. The idea of the geological column was developed in the 19th century by geologists and palaeontologists who studied rocks and fossils from various locations around the world. They noticed consistent patterns of sedimentary layering and fossil succession that allowed them to propose a coherent timeline of Earth's history.
The standard geological column is typically divided into four main eras:
Precambrian: This is the oldest and longest era in Earth's history, covering about 88% of geological time. It is further divided into several eons, such as the Hadean, Archean, and Proterozoic, which include the earliest known rocks and evidence of life on Earth.
Paleozoic: Following the Precambrian, this era covers a significant span of time and is marked by the rise of complex life forms, including fish, amphibians, and early reptiles. It includes periods like the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian.
Mesozoic: This era is often referred to as the "Age of Dinosaurs" and includes the Triassic, Jurassic, and Cretaceous periods.
Cenozoic: This is the most recent era, spanning from the end of the Mesozoic to the present day. It includes the Paleogene and Neogene periods, as well as the current ongoing period called the Quaternary.
It's important to note that the geological column is a general representation of Earth's history, and local geological variations and unconformities can complicate the complete picture. Nonetheless, it serves as a valuable tool for understanding the relative ages of rocks, their approximate deposition sequence and the timing of events that have shaped the Earth over time.
Although it is usually considered to have been laid down over hundreds of millions of years (geological or ‘deep time’) there are a number of observations that call that timescale into question. For example, it is well known and agreed that catastrophic processes of deposition can accelerate the usual ‘slow and gradual’ processes by orders of magnitude [https://creation.com/secular-neocatastrophism ]. Another evidence of rapid formation of the geological column is that soft tissue is found in pre-Cambrian layers [https://doi.org/10.1038/srep03497] as well as Quaternary layers https://doi.org/10.1038/s41586-021-03224-9 ]. In many case the soft tissues have the same form and features irrespective of the age estimates made according to the geological time [Schweitzer et al, Proc. Roy.Soc, B, 2007 (fig 3) doi: 10.1098/rspb.2006.3705). How could soft tissue have remained looking the same over millions of years…?
There are now more than 120 papers in peer-reviewed journal articles reporting soft tissues in dinosaur and other deep-time organic remains. These scientific papers describe biological material, including tissue and DNA, remaining inside fossils. A full list, which is being continually updated, is provided here: *List of Biomaterial Fossil Papers
Example papers for this topic:
(47) Soft tissue and cellular preservation in vertebrate skeletal elements from the Cretaceous 2007
*This list of biomaterial papers can provide useful information for research and posting on topics within the Dinosaur Project Community. Thanks to researchgate.net for making this list freely available.