Geodiversity is the abbreviation for 'geological diversity' and refers to the non-living portion of the planet, while the term biodiversity describes the living portion. Soil, for instance, is part of the Earth’s geodiversity but the micro-organisms that live in it are part of the planet’s biodiversity. Although geodiversity is not alive, it is key to sustaining life on Earth; there would be no biodiversity without geodiversity. 

Geodiversity offers sustainable solutions to pressing global challenges including: climate change, by establishing natural carbon sinks that effectively store carbon dioxide; disaster risk reduction, as data about geological foundations allows us to construct resilient structures that withstand natural hazards; responsible resource extraction, as geological insights guide responsible extraction practices, ensuring minimal disruption and environmental degradation; and biodiversity loss, as geology defines and shapes diverse ecosystems, in which biodiversity can thrive. However, not most people are unaware of the crucial role geodiversity plays in our daily lives. That is why UNESCO has established International Geodiversity Day.

Geologist Jack Mathews is one of the founding figures of International Geodiversity Day. ‘This year’s theme, “Geodiversity is for Everyone”, has a two-pronged focus’, he explains.  ‘It underscores our collective reliance on geodiversity for our own wellbeing, and that of the planet we call home. In parallel, this year’s theme advocates for widening participation in the geological sciences, which are actually very vast.’

There are so many disciplines to choose from. Here are some examples: palaeontology, the study of fossils; palaeoclimatology, the study of ancient climates; volcanology, the study of volcanoes; astrogeology, also known as exogeology, the study of celestial bodies such as other planets, moons and asteroids; and medical geology, the study of health risks of geological origin, such as the presence of natural arsenic in groundwater.

Here are seven compelling reasons why geodiversity is for everyone:

Consider the device on which you’re reading these very words. Ten years ago, its core components, such as lithium and cobalt, were probably hundreds of metres beneath the Earth’s surface.  Look around you. Everything you see that has been fabricated by humans will have been sourced from one of the 90 chemical elements that exist on Earth, those listed in the Periodic Table. The bulb that may be illuminating your room will contain aluminium, silicon, phosphor, gallium and copper, for instance. Your books will have been printed using pigments, binders, solvents and other chemicals obtained from minerals. 

The  geological sciences have fundamentally shaped  our societies. Consider how humanity defines the great ages of human development. We talk about the Stone Age, the Bronze Age and the Iron Age. We talk about the Industrial Age of Coal, beginning in the 18th century, and its successor, the Industrial Age of Oil. We talk about living in the Silicon Age, in tribute to the first commercial microchip in 1971, which paved the way to the first personal computers. What do all these items have in common: stone, bronze, iron, coal, oil and silicon? They all come out of the ground.  We could also cite copper, quartz, tin, uranium, zinc, gold, diamonds and so on, all essential ingredients of modern industries.

Are you curious to know what lies beneath your feet in the hidden depths? In Manhattan, New York, you’d find schist if you dug deep. Schist is a metamorphic rock strong enough to support the city’s many tall buildings, one of the reasons why Manhattan has become an architectural hub for skyscrapers.  In many regions across northern Italy, you’d find marble underground; extracted for over 2,000 years, marble has been used for many buildings. How about underneath Cairo, the capital of Egypt? Here, you’d find foundations made of limestone, used by the ancient Egyptians to construct many of the city's monuments, including the famous pyramids in Giza. 

You might notice how the architecture changes in colour, structure and style, as you travel to different parts of the world; humans have traditionally used these geological resources lying right beneath their feet for construction.

Look at how these mitata (shelters) in the Psiloritis UNESCO Global Geopark in Greece blend into the landscape. Shepherds used the local, platy, dry-stone to build homes, as it made them totally weatherproof and was fully adapted to the landscape. These shelters are still used today for cheese production. 

One way to get involved with geodiversity is to consider links between the geology of your region to local artistic creation and cultural identity. In the Mixteca Alta, Oaxaca UNESCO Global Geopark in Mexico, local communities extract pigments from the volcanic soils to create unique pieces of pottery and to paint. Geological materials are essential for their art. 

Sculpture too, is a form of artistic expression that draws heavily on geodiversity. Think, for example, of the masterpieces by Italian artist Michelangelo (1475-1574), which were made of marble.

Such practices illustrate how Earth's diverse materials influence and shape local traditions and artistic expression.

Geodiversity connects us to ancient life forms, like those preserved in fossilized remains, and helps us to understand the Earth’s origins. By understanding past events through the lens of palaeontology, palaeoclimatology, volcanology and other geological sciences, we can predict the impact of future events. 

Our home is a staggering 4.6 billion years old. During that time, the Earth has witnessed events ranging from a collision with a planet the size of Mars in its infancy, to a global ice age when the surface of our planet almost completely froze over. It has witnessed the evolution of life punctuated by at least five periods of mass extinction. The continents have continually shifted position, oceans have come and gone, sea levels have risen and fallen. We know all this because the Earth has preserved memories of these events in the rocks that cover its surface. The memory of our planet is possibly the greatest story of all – and geologists perhaps the best story-tellers! Moreover, it is a story in serial form, for the plot is still unravelling as geoscientists piece together the puzzle of our past. A fossil or rock sample can tell you so much, if you know how to read it.

The aim of a geopark is to do just that, to teach local communities how to ‘read’ their history, for knowing about the past helps us to understand the present and prepare for the future.  We know that the English Riviera Global Geopark lay under the sea, south of the equator, about 375 million years ago, thanks to the hard limestone rock in the geopark, which is composed of layers of shells and bones from marine organisms – the latter use limestone to build their shells and skeletons. By 280 million years ago, this geopark lay just north of the equator and was part of a vast desert. We know this because the red sandstone in the geopark dates from this period and sandstone tends to form in deserts.

This 5,000m thick coastal outcrop in the Basque Coast UNESCO Global Geopark in northern Spain reveals, layer by layer, a practically continuous record of some 60 million years of the history of our planet. One of these layers marks the last of the five mass extinctions of the Earth’s history. This event was probably caused by a large asteroid striking the Earth some 65.5 million years ago in Chicxulub, Mexico, which led to the demise of the dinosaurs. In the cliffs, there is a very thin black layer of clay (3−5 mm) containing a high concentration of iridium, microtectites and soot. The iridium can only be of cosmic origin, since iridium only exists in tiny concentrations on Earth. As for the microtectites, tiny droplets of glass formed by the melting of the Earth’s crust, they testify to the extreme heat generated by the impact. And the soot? It records the fires which subsequently raged.

It is often said that, if we think of all the living species on Earth -  in other words, the planet’s biodiversity - as the actors in a play, then geodiversity is the stage on which the play is set. Geodiversity underpins all of our environments and ecosystems and, unless we conserve geodiversity, we cannot protect biodiversity.

Despite water covering 71% of the planet’s surface, 97% is saltwater, unsuitable for humans to drink or for use in agriculture. Of the remaining 3% that is potentially available to us, more than two thirds is frozen in ice caps and glaciers. Less than 1% remains available to sustain life on Earth. The majority of this freshwater (98%) flows underground in aquifers which weave their way through spaces in the rock and soil pores and through fractures in rock formations. Groundwater actually comes from the surface; it seeps into the ground and is filtered by rocks and sediments before reaching an aquifer, making groundwater some of the purest freshwater of all.

Whether you would like to become a professional geologist, teach or simply practice geology as a hobby, geodiversity offers you a lifelong opportunity to understand and appreciate the world around you. 

Take inspiration from 16 year-old Aswatha Biju, hailed as ‘India’s youngest palaeontologist’. Aswatha started her fossil collection at just 10 years of age. She has since educated over 20,000 pupils across India through her fossil club, the regular newsletters she produces and her talks to schools. She hopes to see changes in the field of geodiversity education in the coming years. 

For Geodiversity Day this year, Aswatha is organising an event that combines play modelling, origami, storytelling, puppetry, songs and poetry to present the diverse facets of geodiversity and palaeontology.

Geological heritage, or geoheritage, refers to geological features, landforms and landscapes that hold scientific, educational, cultural, aesthetic or touristic value. Mining, tourism, climate change and urbanisation are just some of the potential hazards faced by geoheritage. For instance, Egyptian scientists recently discovered that fossilized remains dated to 43 million years ago belong to Phiomicetus anubis, a previously unknown species of four-legged whale. The fossil was discovered southwest of Cairo near the UNESCO World Heritage site of Wadi Al-Hitan, which translates as Whale Valley. Wadi Al-Hitan contains invaluable fossil remains of the earliest, and now extinct, suborder of whales, Archaeoceti. These fossils represent one of the major stories of evolution: the emergence of the whale as an ocean-going mammal from a previous life as a land-based animal. In order to conserve this World Heritage site, no vehicle access is permitted and ecotourism is restricted to certain zones.

In fact, the scope of geoconservation is not limited to Planet Earth! Clare Fletcher is a PhD candidate in Sydney, Australia, who is creating an exogeoconservation framework for Mars! Exo = space; geo = geology; conservation = the protection of sites. Clare looks for signs of potential past life on Mars, as well as ancient environments in which life might have formed and existed. Clare is working on how we can protect these sites for future learning and study.