This is a polygon coverage that represents areas underlain by the coal-bearing Calico and A-sequences of the Straight Cliffs Formation east of 112 degrees of longitude. It differentiates between areas that contain the entire coal-bearing interval and areas where the coal-bearing strata are partially eroded. The outermost polygon defines the base of the Calico and A-sequences. The inner polygon shows where the complete coal-bearing interval is preserved. The area between the outer and inner polygon shows where the coal-bearing rocks are partially eroded. The northern boundary is delineated by the Paunsaugunt fault and volcanic rocks of Tertiary age.