Taking Geology Seriously
The quest for meaning has always captivated humanity. Ecclesiastes, a Biblical text written millennia ago, reflects this timeless concern. In its opening verses, the author contrasts the fleeting nature of human life with the enduring presence of the Earth. Through poetic descriptions of the natural world, the text uses the Earth’s seeming constancy as a foil for the human condition.
As a college student majoring in biology, my curriculum required physics and chemistry, yet geology never entered my orbit. Over time, however, I have developed a deep fascination with the processes that have shaped our planet across eons. Despite Ecclesiastes’ portrayal of the Earth as static, it is, in truth, an ever-changing marvel, its transformations unfolding over timescales measured in billions of years.
Wonderful Tourist Destinations
The world is rich with geological wonders that draw millions of visitors each year. I have been fortunate to visit some of these breathtaking sites—such as the Grand Canyon, essentially the entire island of Iceland, and Vietnam’s Ha Long Bay’ enormous karst formations. Each of these locations serves as a natural classroom, showcasing the forces of geology and geophysics. Just as growing awareness of biodiversity emphasizes the importance of ecological niches, so too should we consider the geological underpinnings of these environments
What is The Holocene? What is the Anthropocene?
Today, we are living in the Holocene epoch, which began a mere 11,700 years ago, marking the end of the last Ice Age. The term itself derives from Greek—holos meaning “whole” and kainos (morphing into cene) meaning “new.”
Recently, there has been a push to recognize a new, more recent epoch: the Anthropocene, derived from anthropos, the Greek word for “human,” to reflect humanity’s profound impact on the planet. The International Union of Geological Sciences (IUGS), which governs such designations, has debated whether human activity has sufficiently altered the geological record to merit this recognition.
Although the Anthropocene remains an unofficial term, it sparked fascinating discussions about its potential starting point. Proposed markers include:
- The onset of the Industrial Revolution, when carbon dioxide and methane levels began to rise.
- The year 1945, when radioactive fallout from atomic bombs entered the soil worldwide.
- The mid-20th century (1950–1954), marked by spikes in radioactive plutonium as well a rise in carbon particles, and nitrates from industrial activity and the widespread use of chemical fertilizers.
In 2024, the IUGS ultimately decided against formally adopting the Anthropocene.
Twentieth-century technofossils in inundated landfill deposits at East Tilbury on the River Thames estuary. The landfill is being eroded by tidal surges as sea level rises. Here are objects of glass, ceramic, brick, tile, concrete, etc. Lighter materials such as plastics have been carried away by the tides, leaving heavier items behind.
Description of the photo by the photographer.
And Now for the Hadean Eon
For the moment, let us pivot to Earth’s earliest history: the Hadean Eon. This is the first of four geological eons by which scientists measure deep time. Spanning roughly 500 million years after Earth’s formation, ending 4 billion years ago, the Hadean evokes its namesake, Hades, the Greek god of the underworld. During this era, the Earth’s surface was molten, battered by celestial debris, and utterly inhospitable. Although there were gases in the atmosphere, probably derived from volcanic activity, they were unbreathable. They included hydrogen sulfide, methane and a large percentage of carbon dioxide.
A major event Hadean event was the formation of our Moon. The hypothesis involves a small ancient planet, Theia, about the size of Mars, colliding with the Earth approximately 60 million years after the Earth’s creation. This impact is believed to have ejected material that coalesced to form the Moon. As Earth cooled, lighter elements rose to form the crust, while heavier elements like iron and nickel descended to create the Earth’s core.
More Eons
Eons are subdivided into smaller and smaller units of time: eras, periods, epoch, and ages. Earth’s geologic history is broken into three more eons – the Archean, Proterozoic, and Phanerozoic. Sometimes the Hadean, Archean and the Proterozoic are lumped together as the Pre-Cambrian and lasted altogether about 4 billion years. Although we live in the most recent moment of the Phanerozoic eon, it begins with the Cambrian period 539 million years ago. The name “Phanerozoic” derives from the Greek phaneros (visible) and zoe (life), reflecting the period’s abundance of life forms visible in the fossil record and seemingly the beginning of life forms.
The Phanerozoic’s three major eras are based on the fossil evidence which reflect the emergence and evolution of life forms found embedded in specific rock strata. These fossils indicate climate shifts, tectonic activity, and volcanic events, serving thereby as markers of geological as well as biological change.
The Phanerozoic Eon eras:
The Paleozoic Era (Ancient Life) – 539-252 million years ago
Lasting approximately 280 million years, this era saw an explosion of life forms that led to the evolution of arthropods, mollusks, fish, amphibians, reptiles, and mammals. Life transitioned from oceans to land, and plants developed. The era ended with a mass extinction event, wiping out 96% of all species, possibly due to volcanic eruptions, asteroid impacts, or sudden methane releases.
The Mesozoic Era (Middle Life) – 252-66 million years ago
Spanning roughly 185 million years, the Mesozoic is often called the “Age of Reptiles” due to the dominance of dinosaurs. This era ended with the asteroid impact that created the Chicxulub crater in the Yucatán Peninsula, Mexico.
The Cenozoic Era (New Life) -66 million years ago-present
Beginning 66 million years ago, this era is known as the “Age of Mammals.” It has seen the gradual development of animals and plants into forms that are familiar to us today.
The story of Earth—written in stone and fossil—reminds us that the planet, though vast and ancient, is an intricate tapestry of change. The tale of Earth’s formation and transformation is nothing short of enthralling.
fascinating and thought provoking
What a wonderful topic – geology drives so much of our lives without our taking notice !
Even little Israel has geological wonders –
For starters:
a) The ‘Big Juba’: https://tourgolan.org.il/en/listing/the-great-volcanic-crater-the-great-juba-in-the-odem-forest/
b) The regional movement of tectonic plates and all that it created, down the Jordan Valley including the Dead Sea itself!
Thanks for exciting your readers about geological history and its impact on us today.
https://www.earthmagazine.org/article/travels-geology-dead-sea-rift-salty-soaks-and-ancient-earthquakes-storied-land/