What is Organic Geochemistry?

Let’s break it down:

Organic means coming from living things.

Geo or geology is the study of the Earth.

Chemistry is the study of substances.

So, Organic Geochemistry is the study of substances that make up living things to understand more about the Earth. All living things are made up of small parts called molecules that are made of carbon. We call these carbon molecules ‘molecular fossils’ or ‘biomarkers’. Biomarkers can be found in all kinds of geologic deposits, such lake sediments, ocean floor sediments, peat bogs and more!

What are biomarkers?

Biomarkers are tiny fossils left behind by living things. Although we cannot see them even with the help of microscopes, we can measure them with scientific instruments. These tiny fossils can tell us even more information than larger dinosaur fossils!

An example: Biomarkers can tell us what the temperature was 20,000 years ago when large parts of Earth were covered in ice sheets!

What can biomarkers tell us?

There are many different types of biomarkers and each one can tell us a lot of information about the past environment, such as past temperature, past rainfall amount, or changes in past plant communities.

An example: Biomarkers suggest that summer temperatures on Antarctica were as high as 25°C (77°F) around 55 million years ago. Scientists have also found palm tree and rainforest pollen from Antarctica 55 million years ago!!


Biomarker: Who makes it? What does it measure?
Alkenones Algae called haptophytes Past water temperature (lakes & oceans)
Plant leaf waxes Land plants Aridity, rainfall, vegetation change
Hopanes Bacteria in their cell membranes Amount of soil material, changes in the carbon cycle
Tetraethers Archaea & bacteria in their cell membranes Land temperature, ocean temperature, amount of soil material, pH of soil

If you find biomarkers and science exciting and want to learn more, please contact us with your questions.