The valley is "sparsely populated" and runs in a north–south direction with the village of Austwick at the southern valley end. Whilst evidence of human habitation can be dated to the third century, widespread population use did not occur until
Anglo-Saxon farmers arrived in the dale , and they partitioned the land, which is still visible with the scarring of the landscape in
strip lynchets. These strips were used to grow oats in and around Austwick village. Though Crummackdale has not seen as much human interaction with its landscape as other Yorkshire Dales, its recorded history in documents, extends as far back as 1190, when the landowner,
Richard de Morevill, granted some of the fields to
Furness Abbey for 300 marks. Sheep farming dominates the Dale, with some dairy farming occurring on the lower slopes towards Austwick. Austwick Beck used to have what was known locally as a
Washdub. The farmers would get together and dam a low-lying section of the beck, so that they could clean the wool whilst still on the sheep before the sheep were sold. The introduction of chemical sheepwashes, ceased this activity. The great scar limestone at the north eastern end of the dale is quarried at Horton lime quarry on the other side of the hill in
Ribblesdale. To the west of Austwick village, along Thwaite Lane towards
Clapham, is the site of a former tarn, Thwaite Tarn, which was drained around 1811. Much of the dale is inaccessible to motor vehicles, but there are many paths and green lanes that criss-cross the dale. The name of the valley derives from
Middle English Crumb-oke; a
Crooked oak-tree. ==Geology==