Definition of "squelching"

At Beddgelert, where the journey was broken for a luncheon interval, and where there should have been a glorious view, there was nothing for it but to alight on to the squelching ground of an open hillside.

1946 March and April, R. A. H. Weight, “Euston to the North-West”, in Railway Magazine, page 71

The sound of it was scarce louder than the hiss of the rain, a multitude of soft bubblings and squelchings.

1908, Frederick Niven, The Lost Cabin Mine