TIMPANOGOS NATIONAL MONUMENT: STRUCTURAL ANALYSIS OF CAVE SYSTEM FAULTS

The Timpanogos Cave System (which includes Hansen, Middle and Timpanogos Caves) lies in the Deseret Formation, a cherty limestone which has been structurally deformed since its formation 340 million years ago. The cave system is nationally renowned and visited by more than 80,000 unique visitors each year. Despite high visitation and local fame, the cave system’s geology has historically not been well understood, and information that does exist is questionable due to unknown methods.

The Timpanogos Cave System formed solutionally along three fault cracks, which historically have been considered different faults and each have their own names tied to the specific cave in which they are found. These three normal faults strike similarly, at between 030 to 055, and two of the three faults are near vertical, with a slight dip to the south. The Timpanogos Cave fault has some near vertical components as well, though a portion of the fault dips 45N. It has also been held to be the most active, followed by the Hansen Cave and Middle Cave Faults. While slip delineations inside the cave are difficult to come by due to solutional activities and cave formation growth, steep dangerous terrain outside the caves makes information difficult to gather where the faults are exposed. The Timpanogos Cave Fault and The Hansen Cave Fault have moved a similar amount, at about 100 feet each. Previously, it was believed that the Middle Cave Fault had moved a smaller amount, between 10 and 15 feet, but all information gathered shows a much smaller amount, between zero to six inches total.

Reports of the presence of a fourth and fifth fault running through the caves began in the mid 1990’s, and have now been discounted as a result of this study. Due to new research, these two faults are now known to be continuations of the Middle Cave Fault extended into Hansen Cave.

Work is currently ongoing, and further results will be presented at the meeting.