DECISION TIME: Farouk, Jason, Ronald and
Heather-Dawn outside entrance of natural shaft.
Changes in passage of underground river
We had some real adventure when we returned to explore the channel of the river in the interior beyond the Oropouche cavern.
We stopped for a while at the cavern and met the loud squawks, snarls and constant click-clicks as the colony of oilbirds flew around agitatedly on being disturbed in their sanctuary. We noted that this colony continued to multiply. There were nests of three eggs each, tiny chicks, larger and fatter chicks and of course pairs of parents. One large fat baby with new sprouts of feathers was just attempting his first flight when oops! He landed just at the edge of the water.
We exited the cavern and continued towards the natural shaft that would take us down to the upriver section where the Oropouche flowed underground through the mountains. We had to use a length of rope here as descent was very steep and rock falls known as fall outs were common here, forming a loose and precarious floor.
Ronald secured the rope and let himself down first, followed by Jason then this columnist. I just had to see my way down so descended rather unconventionally facing outward and not towards the earth. This proved to be more difficult but I was more comfortable this way. Larger stones or boulders I should say that posed a real danger to us had to be pushed out of the way. As these bounced and smashed heavily on their way downwards the entire interior vibrated.
Farouk began his descent after me. However, whenever his feet made contact with the loose stones, they catapulted towards us below. With the speed those stones came down we saw the danger they posed to us. Farouk realised this too and needless to say he volunteered to take up a position of the timing person outside the shaft.
As he hauled himself back up the rope more loose stones came down and we had to flatten ourselves against the side walls of the shaft. Sorry Farouk. This is the nature of these underground formations.
After further cautious descent of the rubble-filled shaft, we eventually reached the river. We found that this underground passage of the river had changed somewhat. It was obvious that the river had been in flooding conditions many times. Even now, the immediate pool at the base of the shaft was larger and darker than before.
We discerned large fish swimming to and fro as we focused our lights on the water. Overhead, the roof had retained its grand beauty as fringes of stalactites pointed their drip tips downwards, shimmering in the artificial lighting. Disturbed by this lighting of their perpetual darkness, members of a colony of bats flew around.
What was different here though was the immediate bank of the river. Silt was piled higher than before and we had to exercise caution in walking on it because it was still very soft in some parts. On the opposite side, there was no bank as the walls fell directly into the water.
We found that the water was also deeper presenting a real challenge to us to continue upriver. We peered through a low and narrow passage that opened onto another section of the channel. We could just imagine this filled with water in times of flood. Subsequent sections of this channel had less silt or none at all and was more accommodating.
As we followed the course of the river on our return to the base of the shaft, we realised that what had actually happened was that the flooding water had been slowed down by the wall blocking its way. This explained the heavy siltation here.
The rainy season is still ongoing and we look forward to returning perhaps after prolonged heavy rainfall to see just how dramatic this section of subterranean Oropouche could be.