Biodiversity and geology: Termites dig deeper
The role of biodiversity in solving modern day problems should not be underestimated.
By Leon Louw founder of WhyAfrica and editor of the WhyAfrica magazine
Termites and termite mounds are crucial in the healthy functioning of ecosystems in the African savannas. They can also play an important role in exploration geology and many mineral discoveries have been made as a result of studying termite mounds.
Moreover, many communities in Africa use the soil from fungus growing termite mounds as cement to build their traditional houses.
Studies are underway to determine what role harvester termites can play in carbon storage.
Two different termites in Africa
Two different termites are found in Africa each with its own behaviour and ecological role. Harvester termites feed on plant matter. Fungus-growing termites, on the other hand, cultivate fungus as their primary food source.
Harvester termites’ nests are typically underground with only small mounds (or “heuweltjies”) on the surface.
Fungus growing termites live in complex colonies and their nests are elaborate constructions. They bring up material from deep below the surface and it is normally these nests that are used in exploration geology.
Termite mounds and their function
The largest termite mounds in Africa can be found in Southern Africa, particularly in Zimbabwe, Botswana, and South Africa. These mounds are built by Macrotermes species. Some of these mounds can grow to heights of 12 meters or more.
These giant mounds are typically made of a mixture of soil, saliva, and feces, which gives them their durability. They serve various ecological functions, including temperature regulation, and support a wide variety of wildlife.
Termite mounds in geology
Termite mounds have proven valuable in various aspects of geology and exploration. From revealing soil profiles and mineral deposits to helping with hydrological studies and indicating potential geochemical anomalies, termite mounds are a significant natural feature in the realm of geological exploration
In some cases, termite mounds may indicate the presence of mineral deposits below the surface. For example, termite activity may bring up fine particles of minerals such as iron, clay, or even gold, which can be valuable for exploration.
Researchers often examine the composition of termite mounds for “pathfinder elements,” which are chemicals or minerals that may lead to the discovery of larger ore deposits. By analysing termite mound soil, geologists may identify areas to target for further exploration.
Oldest termite mounds on earth
Recently the world’s oldest active termite mounds were discovered in Namaqualand, South Africa, dating back 34 000 years, or since before the last Ice Age when woolly mammoths still existed.
The little hills were discovered by researchers from Stellenbosch University’s Department of Soil Science and Earth Sciences, who collaborated with experts from the Institute for Nuclear Research in Hungary. The findings were published in May 2024 in the journal Science of The Total Environment.
The mounds are inhabited by the southern harvester termite. The previous oldest inhabited mounds – by a different termite species – were discovered in Brazil, and they are 4 000 years old, Stellenbosch University said in a statement.
The ‘heuweltjies’ (little hills) have shown that during their formation, the region experienced significantly more rainfall than today. This wetter climate allowed for minerals such as calcite and gypsum to dissolve and move down to the groundwater. What is interesting is that Namaqualand still has sporadic episodes of intense rainfall, like last winter, which would re-activate the process.
According to the study, the process of soil calcite leaching into groundwater is useful for storing carbon (from the atmosphere) in the ground for a long timeframe.
Essentially, the mounds act as carbon sinks, by removing carbon dioxide naturally from the atmosphere and storing it underground or in soil. Carbon dioxide is one of the greenhouse gases that contribute to rapid global warming, which is why this is important in combating climate change.
The discovery will form part of a study on their carbon storage potential, funded through a joint grant by the National Science Foundation in the US and South Africa’s National Research Foundation.
Termite mound clay to build houses
In Africa, termite mound clay is used in the building of traditional houses, and for producing good quality bricks.
Termite mound clay is pozzolanic in action and accelerates setting times. It has high affinity for water. Extensive research and statistical analysis have shown that reliable concrete of good quality can be produced from clay unearthed from termite mounds.
Termite mounds are remarkable structures, and their role in geology and exploration is often overlooked. However, scientists have found various ways in which termite mounds are used or studied in the context of geology and exploration.
Biodiversity and geology: Termites dig deeper
