Mala Ciancia first provided an overview of geologic history in the New York City area and discussed how Manhattan has a tremendous variety of rock types for such a small area—including Mica Schist, Granite, Pegmatite, Gneiss, Marble, Serpentinite, Mylonite, Amphibolite, and Talc Schist—primarily due to its unique location at the junction of three physiographic provinces: the Atlantic Coastal Plain, New England Upland, and Piedmont Province. She emphasized how understanding the site geology is critical to the planning of any underground project and that the investigation for caverns is an iterative process that includes a review of existing data, a field testing program, and a laboratory testing program. She also spoke about faults, foliation, fracturing, and compared the key geotechnical parameters between tunnels oriented in a north-south direction versus those oriented in an east-west direction.