Science Beneath the Surface

Formed in limestone

Water and time have shaped the cave systems of the Leeuwin-Naturaliste Ridge. 

The caves of the Leeuwin-Naturaliste Ridge have formed over long periods of time as water has moved through limestone. Slightly acidic water gradually dissolves rock, creating and modifying underground voids, passages and chambers.  

As water moves through the cave environment, it can also redeposit calcium carbonate, building cave formations known as speleothems, such as stalactites, stalagmites and flowstones. 

Speleology is the scientific study of caves, including their formation, structure and ongoing change. Through mapping, documentation and condition monitoring, speleological research helps build understanding of how cave systems develop and supports the long-term care of underground environments. 

Connected by water

Rainfall, groundwater and the landscape above influence what happens inside the caves. 

Water movement through the caves is closely linked to the landscape above them. Rainfall patterns, vegetation, fire regimes and land use can all influence how water travels through the landscape and into underground systems. These changes are not always visible at the surface, but they can alter cave water levels, the development of cave formations and the conditions that underground species rely on. 

Hydrology is the study of water: how it moves, where it is stored, and how it interacts with landscapes and ecosystems. In cave systems, hydrological research helps explain the relationship between rainfall, groundwater, catchments and underground environments. 

At Lake Cave, long-term monitoring has tracked water levels, stygofauna populations and catchment health since 2010. This research helps show how climate, land use and groundwater conditions are reflected in the cave environment over time. 

Mammoth Cave provides a visible example of this connection, with a seasonal stream linked to winter rainfall. At Jewel Cave, long-term changes in groundwater conditions have also been reflected underground, including changes to the visible lake once present within the cave. 

Cave atmospheres

Humidity, temperature, airflow and seasonal change influence the environment inside each cave. 

Caves have their own internal conditions. Temperature, humidity and air movement can vary between caves, between different parts of the same cave, and across the seasons. 

Some areas exchange air more readily with the outside environment, while others are more enclosed. These differences can be influenced by cave structure, rainfall, soil processes, groundwater, seasonal weather and pressure changes. 

These natural variations are part of how cave systems function. By monitoring cave atmospheres over time, researchers can better understand seasonal patterns, conditions in different parts of a cave, and the processes that help protect cave formations, habitats and other sensitive values. 

Life underground

Specialised species depend on cave habitats, groundwater systems and stable conditions. 

Caves and the surrounding landscapes support species adapted to underground conditions, as well as animals that use caves and cave landscapes for shelter, breeding or seasonal activity. Cave environments are generally characterised by relatively stable temperature and humidity, creating conditions that are very different from the surface. 

Research into cave ecosystems can include many different forms of life, from aquatic and terrestrial invertebrates to bats and microbial communities. Microbial communities play a role in many cave ecosystems, helping break down organic material, contributing to nutrient cycling and supporting ecological processes where organic matter is limited. 

Among the most closely studied species in cave environments are troglofauna and stygofauna. Troglofauna are terrestrial animals that live underground, often with adaptations such as reduced eyes or loss of pigmentation. Stygofauna are aquatic invertebrates that live permanently in groundwater-fed systems, including crustaceans, worms, beetles and snails. Many are highly localised, and some may exist in very few places on Earth, making them an important focus for ongoing research and monitoring. 

Cave-dependent species can be sensitive to changes in water quality, water levels, humidity, temperature, air movement and habitat condition. Long-term monitoring at Lake Cave is helping researchers understand how changes at the surface can move through underground systems and influence the species that rely on them. 

Caves and the surrounding landscape also provide roosting and shelter habitat for bats at different times of year. Recent research, including at Mammoth Cave, has documented seasonal cave activity in chocolate wattled bats. This research is helping build understanding of how bats use cave environments and why these habitats are important within the broader landscape.  

Records of the past

Fossils, sediments and cave formations hold evidence of ancient environments. 

The caves of the Leeuwin-Naturaliste Ridge preserve records of past environments across long periods of time. Their stable, sheltered conditions can protect formations, sediments and fossil material from weathering and disturbance at the surface. 

Palaeontology is the study of ancient life and the environments those species once inhabited. In the Leeuwin-Naturaliste Ridge caves, palaeontological research has revealed particularly rich fossil material. Mammoth Cave has long been recognised for its palaeontological significance, with more than 10,000 fossils recorded there. These include remains of Australian megafauna that became extinct around 46,000 years ago. A Zygomaturus jawbone, estimated to be around 50,000 years old, remains embedded in the cave wall today. 

These discoveries help researchers reconstruct prehistoric environments in south-western Australia and understand the conditions these species depended on. As dating methods and analytical techniques improve, scientists can build a more detailed picture of ancient ecosystems and the changes that influenced them. 

Cave sediments can also preserve environmental and biological material, helping researchers understand past conditions and the timing of changes within the cave and surrounding landscape. 

Through geochemistry, scientists analyse the chemical composition of speleothems, such as stalactites, stalagmites and flowstones, to examine past rainfall patterns, vegetation change, fire history and climate conditions. This research can contribute to palaeoclimate records for south-west Australia and improve understanding of long-term rainfall and groundwater trends in the region.