Key take home messages from the virtual field trip

We examined two broad groups of rocks: plutonic igneous and contact metamorphic or meta-sedimentary rocks.

The key features of the igneous rocks included:

• they are homogeneous rocks that are uniform for large areas at outcrop and map scales or cut other rocks as planar bodies (dykes or sills),

• they weather into distinctive tors or rounded outcrop shapes that include boulder-like, whale back, and pinnacle shapes,

• they contain medium to coarse crystals (phaneritic texture) because they cooled slowly in the Earth's crust,

• they present equigranular grains (similar sizes) with random orientation and interlocking textures,

• they have sharp intrusive contacts with country rocks (that are contact metamorphosed),

• some outcrops showed enclaves probably formed by mixing of two magma compositions or temperatures making globules of one in the other.

The key features of the contact metamorphic rocks included:

• they formed from a variety of protoliths (parent rocks) so that we saw a range of different minerals and metamorphic rocks,

• all the meta-sedimentary rocks we examined were in between two plutons and so were of high metamorphic grade (high temperature) within the contact aureole as evidenced by high temperature index minerals such as wollastonite,

• evidence that some fluids moved through and reacted with the rocks during metamorphism,

• metamorphism with low differential stress such that minerals are randomly oriented forming a hard metamorphic rocks called a hornfels.

What to submit (EESC1150)

At the end of the field trip, please compose a blog like those that you have written for each week of session. Reflect on your learning on the field trip. Attach your completed field trip work sheet and your field note book to the blog post. Please complete your blog within a few days of completing the field trip.