Rivers to nowhere

When I was a little boy, my outdoorsy uncle told me that, should I ever get lost east of the Mississippi, all I had to do was walk down hill. Eventually I would find a stream, and following that stream would lead me to a road crossing (or, in very rare cases, the ocean).

Needless to say, this algorithm is of little use in central Australia.

The following picture shows a series of closed drainages in southern NT that I flew over on the way home from my last trip.


These drainages, like many small rivers and creeks in central Australia, terminate in a dune field. Some of the larger rivers may actually reach a playa or salt pan, and most of the area of Australia is closed drainages. The following picture from the Stirling ranges in WA shows that even quasi-coastal mountains (45km inland) have streams which terminate in salt flats.


I’m still not sure how working out here will change my views on sedimentation and hydrology. But I do now think of flows as a series of discrete events, rather than a continuous process. While these viewpoint seem odd when applied to permanent rivers, as long as sediment transport is governed by short to medium period flood events, it might be worth hanging on to.

Similarly, I find myself assuming that weathering must eventually result in downstream formation of calcrete/silcrete/ferricrete, depending on surface and ground water composition. I still need to wrap my head around the idea of water just shuffling minerals between pedogenic phases of a closed system, instead of washing stuff away into a vast ocean.