What distinguishes a glacier from a perennial snow patch?
In an area where there is more snowfall than summer snow melt, perennial snow patches appear in the mountains and remain at the end of summer. No longer only a mass of ice and snow, it is a glacier! Staging area on a glacier’s névé, the area covered with snow throughout the year.
What makes snow a glacier?
Glaciers are made up of fallen snow that, over many years, compresses into large, thickened ice masses. Glaciers form when snow remains in one location long enough to transform into ice. Due to sheer mass, glaciers flow like very slow rivers.
What is evidence that a glacier once covered an area?
The most apparent evidence is of course the glacial drift itself. Glacial drift refers to the rock material ground up and transported by a glacier and deposited by or from the ice (till) or in water derived from the melting of ice (outwash or lake sediment).
What is the best evidence we see that a land was once covered by glacier?
Geologists found evidence that tropical areas were once covered by glaciers by examining ancient tropical rocks that are now found in remote northwestern Canada.
What are the two types of crust?
Earth’s crust is divided into two types: oceanic crust and continental crust. The transition zone between these two types of crust is sometimes called the Conrad discontinuity. Silicates (mostly compounds made of silicon and oxygen) are the most abundant rocks and minerals in both oceanic and continental crust.
What are 3 main types of plate boundaries?
There are three main types of plate boundaries:
- Convergent boundaries: where two plates are colliding. Subduction zones occur when one or both of the tectonic plates are composed of oceanic crust.
- Divergent boundaries – where two plates are moving apart.
- Transform boundaries – where plates slide passed each other.
What physical features are caused by plate tectonics?
Deep ocean trenches, volcanoes, island arcs, submarine mountain ranges, and fault lines are examples of features that can form along plate tectonic boundaries.