Imagination has led us to create incredible worlds that we can only conceive by observing our own natural limits. None of this would be possible without a vast and overwhelming geology, present in the ancient layers of the Grand Canyon or on the summits of volcanoes doomed to erupt. Geology is felt in the erratic boulders transported by vanished glaciers, and in the deep coal mines that millions of years ago were forests during the Carboniferous period. We also find it in the seismic waves traveling through the Earth’s interior, generating earthquakes, or in the methane deposits trapped in the ocean depths.
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All these landscapes and formations share a common thread: Earth’s geodynamics. This generates constant vitality on our planet, giving us divergent and convergent tectonic plates that create continents, and ocean currents that promote a climate suitable for the emergence of the genus Homo. All of this is geology.
Before geology
For this reason, since ancient times, landscapes have captivated the curiosity of scholars and thinkers. For example, Ibn Sina — better known as Avicenna — described in his work “The Book of Healing” the formation of mountains as a slow process that required an enormous amount of time. This is precisely one of the fundamental pillars for understanding geology: time. Or rather, the staggering amount of millions of years necessary for geological processes to occur.
To understand this, humanity has had to navigate blindly through a sea of research that led us to realize that, for a river like the Amazon river or the Nile to form, something more than the intervention of an ancient god is needed.
In 1650, Archbishop James Ussher, through the analysis of biblical genealogies, determined that the Earth had been created on October 22, 4004 BC. At that time, the official age of our planet was established at around 6000 years, which meant that — according to Christianity — our planet had emerged during what we now know as the Stone Age. Shortly after, Nicolas Steno laid the fundamental principles of stratigraphy in the 17th century, becoming the father of geology. Although his influence extended in the following decades.
The Uniformitarianism arrives
Before monotheistic religions, various cultures understood the Earth as a pantheon of wild-natured gods who embodied natural processes at different moments of creation. The word “geology” shares its root with Gaia, the primordial Greek goddess who gave birth to Uranus, the sky, and was united with Cronus, time. In scientific terms, we have adopted the name of this goddess to designate the science that studies the origin, structure, and processes of the Earth.
Although the forces that shape the landscape have been present since the beginning of our planet, about 4.6 billion years ago, it was not until the 17th century, during the height of the Baroque period and the Scientific Revolution, that geology began to establish itself as a science. In this context, a shift in thinking emerged, partly driven by the Church’s explanations, which relied on catastrophism to justify major geological changes through divine and sudden events, such as the Great Flood—a myth present in several earlier religions—that supposedly caused the first great biblical extinction, with Noah as the preserver of biodiversity.
One of the key figures of this era was James Hutton. In 1795, he published his “Theory of the Earth,” a book that established the foundations of uniformitarianism, a concept opposed to biblical catastrophism. Hutton proposed that the same physical, chemical, and biological laws that operate in the present have acted throughout geological time. This means that, to understand past processes, we must observe those occurring in the present, as they repeat cyclically, although not always predictably.
What more can we require? Nothing but time
James Hutton
Finally, in 1907 the first radiometric age of the Earth was obtained, empirically and irrefutably demonstrating that the history of our planet is measured in millions of years. Thus, the laws of this science called geology have been established and refined up to the present day.
Geology as a science
Geology is divided into two main areas: physical geology and historical geology. Physical geology studies the materials that make up the Earth and analyzes the internal and external processes that act upon them. On the other hand, historical geology seeks to reconstruct the origin and evolution of the planet over time, establishing a chronology on a scale of millions of years. To do this, it considers both the physical and biological changes that occurred in the past. Obviously, both disciplines complement each other.
Understanding the changes that have shaped our planet is not an easy task. As we have seen, some processes can extend over millions of years—such as the formation of a mountain range—while others can occur in a matter of hours, like a rockfall. Additionally, these processes can be studied in the field on a macroscopic level, using hammers and sketchbooks, or in the laboratory, with the help of a microscope, analyzing the composition and texture of rocks.
As we will see later, the vast amount of information we can extract from our planet has given rise to a multitude of specialized branches within geology.
A planet in constant motion
The planet we live on is governed by a fascinating geodynamics, where geological and biological connections intertwine in a universal concert. Tectonic plates create and destroy continents, and the traces of these processes have been recorded in rocks that appear simple and unremarkable.
The Earth changes and will continue changing. We are part of it, of its natural resources, its geological hazards, its energies, and its minerals, which we use to build technology. We plan cities on unstable land; we know that volcanoes are dangerous, yet their fertile soils provide us with great wealth. In the Pyrenees, for example, we find large granite plutons that 300 million years ago were magma chambers that never erupted.
What lies beneath our feet remains mysterious, but it is no longer so unknown. Now we know that the Earth is not hollow, that there are no reptilians lurking or Godzilla hiding his family. However, even if we dismiss all science fiction and religious explanations, nothing will be stranger than reality itself, nor more astonishing than finding the origin of life in a simple rock.
Bibliography
Essentials of Geology. Frederick K. Lutgens and Edward J. Tarbuk. 2006
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