Abstract:

Seventeen blind valleys of the Yarrangobilly karst are describes especially with reference to shifting streamsink location and phases of downward incision. A series of measures of them, based partly on ground traverses and partly on contoured maps, is presented and discussed. Standard morphometry of the basins ending in the blind valleys is presented also. These truncated basins are shown to have normal morphometric relationships. Whether a stream sinks or not in the limestone appears generally to relate to the length of limestone to be crossed in relation to full stream or basin length, though basin relief ratio may intervene. The hypothesis that there will be dynamic equilibrium between the dimensions of blind valleys and sinking stream catchments finds only limited support in the data. This is because underground stream capture represents an abnormal event in drainage basin development liable to upset equilibrium relationships and its timing may be adventitious in that development. With a larger population of blind valleys to be analysed, this factor of timing might become subordinate, and a batter predictive model of blind valley volume be derived.