In Iowa only 73 wells penetrate into MRS rocks
(click for map locating MRS drill data).
Most of these wells (49) are clustered into three areas,
where gas storage facilities were developed in structural
domes that formed in basal Paleozoic sandstones above Iowa
Horst-bounding faults. Of these gas storage wells, 44
penetrate into mafic igneous rocks (a total penetration of
388 feet -116 m), and 5 penetrate into MRS clastic rocks
(total penetration of 40 feet -12 m). The gas storage
drillingproduced cores from 10 wells, 6 of mafic rocks
(totaling 97 feet - 29 m) and 4 of clastic rocks (totaling 79
feet - 24m). The #1 Sharp well in Webster County penetrated
57 feet (17 m) of basalt, including all or parts of three
individual lava flows separated by weathered, vesicular flow
tops.