Looks like an eroded anticline. Sometimes this is caused by gypsum/salt [not just halite...] deposits (salt domes) being pushed up from beneath by tectonic pressures. The salt/gypsum dissolves quickly, especially after the uplift causes cracks in the overlying rock layers, then it dissolves and all you have left are the ridges of the anticline outlining the original uplift - in effect, sort of a 'popped' rock 'bubble' - if you consider that it takes [approximately, depending on the size and tenacity of the overlying rock layers...] a couple million years to dissolve the center...
makes some neat rock formations... check out "upheaval dome, utah" on GoogleEarth if you want to see an excellent examply - although they're still debating the origins of that formation. Some think it may be an impact crater...
Now now... you should know better than that...
The formation was caused by the receding flood waters. Where they receded to, I'm not sure...