Today was another long driving day, but the road was in reasonably good condition and the traffic was comparatively light, so it was just a matter of getting into the zone.
One thing worth mentioning is that skirting the east side of the Meratus mountain range we came across a thick sequence of limestones that have given rise to the most beautiful karst landscape. This is not a small unit, but extends for kilometers, forming very distinctive pillars that go far into the mountains. I believe this indicates that this area is undergoing active uplift so the streams between the pillars are entrenching themselves very rapidly in the easily dissolved limestones.
But besides their beauty, these limestones look to me very similar to those we encountered when we were going to the south on the west side of the mountains. If the Meratus massif is indeed a subduction zone complex (remember for example the blueschists we saw a couple of days ago), then this symmetrical distribution of limestones on both sides of the complex begs for some explanation. Assuming that both limestone sequences are the same age, then one could draw a similarity to the anticlinal structure of Mount Diablo, in California, where a serpentinite diapir forms the core of a double-plunging anticline. Might be a hypothesis worth testing when looking a the geologic map of the area.
The other break in the monotony of the long drive came when we reached the Balikpapan estuary. We had the option of going all around it, but instead chose taking the ferry to go across it. Happily the landings are not just in front of each other, so we had a chance to see the sights as we steamed upstream. "The sights" were many ships standing at anchor, a refinery, a power plant, and a portion of the city that has a huge mosque and reminded me a bit of approaching Istanbul by sea.
Tomorrow Friday we have to take care of the car and other business, and on Saturday we will say goodbye to Borneo and arrive in Selawesi.
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