Question

1. what rock type is the palisades sill?
2. folded and faulted crystalline (igneous and metamorphic) rocks underlie most mountains. in what two ways are the catskills different from most mountains?
3. the rocks of the catskill mountains were originally deposited as what kind of landform?
4. what characteristic of the underlying bedrock is responsible for the location of the hudson and mohawk river valleys?
5. what global event probably pushed up the high mountains where we now find the hudson highlands and taconic highlands?
6. where might you look in new york state if you wanted to find fossils of dinosaurs?

the erie-ontario lowlands borders the great lakes. layers of sedimentary rocks in this region dip gently to the south. the glaciers left many characteristic features that dominate the landscape including moraines, drumlins, eskers, and kames. the glaciers also deepened and dammed the valleys now occupied by the finger lakes. niagara falls formed where the niagara river runs over a layer of resistant dolostone, see figure 15-6.

Explanation:

1. Sills are intrusive igneous rock bodies formed when magma intrudes between sedimentary layers and solidifies.
2. Most mountains have folded/ faulted crystalline rocks; the Catskills are flat-lying sedimentary rock uplands (plateau eroded into mountains).
3. The Catskills’ sedimentary rocks were deposited in a low-lying, water-covered area (delta/ floodplain) from ancient rivers.
4. Rivers follow paths of least resistance; softer bedrock erodes more easily, forming valleys.
5. The Hudson and Taconic Highlands formed from the collision of tectonic plates (Appalachian orogeny).
6. Dinosaur fossils are found in Mesozoic sedimentary rocks; in NY, these are in the Newark Supergroup (e.g., Palisades Sill area or Connecticut Valley adjacent regions).

Answer:

1. Igneous rock
2. The Catskills are composed of flat-lying sedimentary rocks (not folded/faulted crystalline rocks) and are eroded plateaus rather than tectonically uplifted mountains with deformed rocks.
3. A delta or floodplain (low-lying depositional landform)
4. The bedrock is softer and more easily eroded.
5. The collision of tectonic plates (Appalachian mountain-building event)
6. In areas with Mesozoic sedimentary rocks, such as the Newark Supergroup regions (e.g., near the Palisades or southern NY).