Seal Cove
Seal Cove is located in the town of Tremont on the South-Eastern side of the Island. Different rock types and their formations help to tell the geologic history of the area, along with providing evidence of volcanic and glacial activity.
Seal Cove field site in red
Photo by: Google.com/maps
Edited: Sam Meuse
Ellsworth Schist
The Ellsworth Schist was formed in the late Precambrian age about 600 million years ago (Lowell, 2012). The Ellsworth Schist is metamorphic rock. During its formation it was exposed to extreme heat and pressure from tectonic events. Ellsworth Schist is foliated dark gray and green with the minerals quartz, feldspar, and mica visible.
Ellsworth Schist
Photo by: Sam Meuse
Image of Shatter Zone, with a close up of the granite structure
(K-feldspar, quartz, and hornblende).
Photo by: Sam Meuse
Shatter Zone
The Shatter Zone formed during the Silurian period. (Lowell, 1988). This is the area around the magma chamber of the past supervolcano. When the volcano erupted, the resulting explosion shattered the rock around it (Ellsworth Schist). This gave rise to pieces of The Ellsworth Schist becoming lodged in the still molten Cadillac Mountain granite in the surrounding area.
Basalt Dyke
Basalt is an iron rich igneous rock, that while it was magma intruded into The Ellsworth Schist, because the schist was cold by comparison, it caused the basalt to cool quickly. The dike measures about 50 feet across.
Basalt Dyke, with the intrusive contact in green, and directional measurment
Photo by: Sam Meuse
Photo of a small Roche Mountonnée, illustrating the movement of the glacier.
Photo by: Sam Meuse (Marshak 2012)
Glacial Features
All across Seal Cove small roche mountonnées are visible. A roche mountonnée is known for a gradual sloping side, and then steep slope on the opposite side. This is caused when a glacier passed over a rock surface gradually carving down one side of a rock, or mountain, and breaking, or plucking, the other. (Marshak, 2012)
Photo showing a crescentic fracture in a graite surface.
Photo by: Sam Meuse (Marshak 2012)
Another sign of glacial activity in this area is the presence of crescentic fractures and glacial striations. Crescentic fractures are caused when a glacier passes over a surface and exerts immense pressure on that surface. When the glacier begins to slide it will push into the surface before slipping free, leaving a crescent shape behind. Glacial pressure and movement also produced scratches and gouges oriented in the direction of a moving glacier known as glacial striations. (Marshak, 2012)