A bajada is essentially a sea of small pieces of rock, alluvial debris from one or more mountain ranges in an arid
area, especially the Basin and Range
country of western North America
Bajadas start out their lives as small alluvial fans
, piles of debris from cracks in a newly-formed mountain range. As the cracks turn into valleys, the fans grow. Eventually they merge together into bolson
Fans and bolsons grow out across the valley towards the next mountain range, which is forming fans and bolsons of its own. Eventually the opposing piles of debris meet each other and fill in the valley. At this point we can call the combined pile a "bajada".
Meanwhile, the remnants of the mountains become smothered in their own debris, until only the peaks stick out like islands in the bajada sea. These remnant peaks are called inselberg