BURIED STREAM PIRACY LEADS TO CAVERN DEVOLOPMENT IN THE MANLIUS LIMESTONE, SCHOHARIE COUNTY, NY

Secret Caverns is a natural cave situated on the northern edge of Schoharie County, NY. The cave developed as a nearly straight vadose-phreatic passage oriented at a 45° angle to the regional dip (tilt of bedding) - without obvious structural or sedimentological control. Previous work by Mylroie (1977) did not explain the caves formation. The purpose of the study is to define the developmental history of the cave system. This could include; 1) multiple joint patterns in the rock providing a passage for water, 2) a fault running through the cave, or 3) a confining layer. In this study, emphasis is placed on answering why the cave is oriented in a direction contrary to other caves in the area. The cave is situated within the Manlius limestone and doesn’t appear to follow any structural controls. The main conduit is formed under a number of large domes along with smaller paleokarst passages feeding it. Our current hypothesis is that the cave formed in respose to a paleostream above ground that fed the domes. Post glacial isostatic rebound formed bedding plane faults in the bedrock that connected the domes forming the passages. A layer of bedrock was tested below a prominent ash layer to see if there was any sedimentological control. A bedrock control layer was sampled from an outcrop along I-88. The limestone was then dissolved in 5 molar HCl and tested against limestone from the cave. Joints were also measured to see if the cave fell along the major joint set. The “confining” layer of limestone reacted 30% less than limestones of the cave passage. Measured joints show a main orientation of 25° azimuth while the cave has a general direction of approximately 160° azimuth. This cave differs from others in the area such as Mcfails and Howe Caverns, both strike oriented passages. It can be concluded that the cave forms in the down-dip direction of the bedding with a minor component of joint control, while the initial influx of water came through joints in the rock.