The Maria fold and thrust belt (MFTB) is a portion of the North American Cordillera orogen in which geological structures accommodate roughly north–south to northwest-southeast vergent Mesozoic age crustal shortening.

Since soils and climate differ across the Maria fold-and-thrust-belt, this regional geologic structure can be considered a "dividing line" for a number of flora and fauna species.

For example, the species range of the endangered California Fan Palm, Washingtonia filifera does not extend north of the Maria fold-and-thrust-belt, or more specifically the Turtle Mountains.

[4] The Maria fold-and-thrust-belt comprises a large number of ranges in the south-eastern Mojave and north-western Sonoran deserts,[1] including the: List of some regional landforms.

(The ~east-west Bill Williams River appears as part of the central and northern perimeter of the Maria fold-and-thrust-belt, approximately paralleling the Rawhide Mountains, a slight northwest range on west end.)