Monday, 13 May 2013

Karst limestone and crabs...

30 degrees Celsius and 75% relative humidity today, but a cool breeze blew on-shore from the South making the heat just bearable.  As we pushed our way through dense undergrowth that seemed determined to snag, pull and slice all members of our team, the temperature and humidity seemed to increase step-by-step and the air became still. Looking over our shoulders back towards where we had left our car, all we could see now was dense jungle, for want of a better term. The ground soon began to get steeper, being the main indicator that we were walking away from the coastal road. We finally reached the base of the limestone wall that seemed as populated with vegetation as the 'path' from the road. Looking up, we could see countless cacti, palms, aloe, mixed with a bright array of tropical plants...all in our path and obscuring the top of the cliff.

Dr Victoria Egerton encourages Dr Mike Buckley not to use the cacti as a hand-hold.
The cliff was severely weathered into a typical karst limestone topography, where dissolution of the more soluble component of the formation left a sharp, almost clinging/sticky surface. The rubber on the soles of our shoes seemed to adhere to the sharp and very unforgiving dolomitized limestone. All member of the team were already drenched in sweet....but we slowly pushed-on, up a vague pathway: one that few had trodden. Finally, at about 40 metres up the rock face, we came to a small ledge and a 1 metre diameter hole, punched into the wall of the sheer cliff. The karst topography had given-up one of its sought-after features...a cave entrance!

Hot, Humid and Happy. Dr Phil finds a hole to explore.
Slowly we donned our caving helmets and crawled into the narrow hole...that soon became narrower and narrower  with awkward twists and turns, combined with tearing dolomitic teeth from the floor, walls and ceiling of the cave. Daylight was soon lost behind us and only the narrow beam of our headlamps picked-out the path deeper into the cave. The humidity was soon oppressive, around 80% rel, and when combined with the 30 C...we were hot, sweaty and miserable. Caving in Britain is at least 20 degrees cooler and half the humidity. However, we had come along way to turn around now. We pushed-on into the cave.

We were soon reduced to crawling on our bellies and pushing our way through tighter and tighter passages, some that led to larger chambers, allowing us to periodically stand-up and stretch our legs. In the corner of a small cavern, something caught our eye...something moving. It seems were were not alone in the depths of the cave system. Somehow, a rather beefy land crab had climbed its way deep into the cave system and seemed happily living in a damp corner.

Cave occupant gets crabby at our presence.
These remarkable crustaceans have evolved to live on land, through 'stiffening' their gills with the same structural biomaterials that construct their tough shelly armour. This prevents their gills collapsing out of water, so the crab has an affective 'lung' that allows its terrestrial life. However, crabs meant trouble for these crunchy scavengers have a nasty habit of ploughing their way through the cave floor debris, often messing-up any possible evidence of prior life in the caves. What might have once been articulated skeletons of a few distinct species, becomes a phylogenetic soup of bones, dust and debris. After surveying the cave for a few hours....we had to retreat to the 'cool' air outside...

Prof. Andrew Chamberlain, Dr Bill Sellers and Dr Mike Buckley emerge from the cave...slightly warm!
This is one cave we will try and LiDAR map later this week, as it holds some rather fun secrets....but more on that later. We only have four days to locate, prospect and map new caves lurking in this tropical karst landscape...that will hopefully not have been 'blended' by the local wildlife.

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