3.1 The rock Cycle

The rock contents of the crust room slowly however constantly being adjusted from one kind to another and also the processes involved are summary in the rock cycle (Figure 3.2). The rock cycle is pushed by 2 forces: (1) earth internal warm engine, which moves material roughly in the core and also the mantle and leads to slow but significant changes within the crust, and also (2) the hydrological cycle, which is the movement of water, ice, and air at the surface, and is powered by the sun.

You are watching: The figure above shows that sedimentary rocks are changed to sediment by ____.

The absent cycle is still active on Earth because our core is hot enough to save the mantle moving, our setting is relatively thick, and we have actually liquid water. On some various other planets or their satellites, such as the Moon, the absent cycle is essentially dead due to the fact that the core is no longer hot enough to journey mantle convection and there is no environment or liquid water.

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Figure 3.2 A schematic watch of the rock cycle.

In relenten the absent cycle, we have the right to start all over we like, although it’s practically to begin with magma. Together we’ll view in an ext detail below, magma is rock the is hot to the point of being totally molten. This happens at between around 800° and 1300°C, depending upon the composition and the pressure, top top the surface and cool quickly (within secs to years) — creating extrusive igneous absent (Figure 3.3).

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Figure 3.3 Magma forming pahoehoe basalt at Kilauea Volcano, Hawaii

Magma can either cool gradually within the crust (over centuries to numerous years) — developing intrusive igneous rock, or erupt ~ above the surface and also cool easily (within secs to years) — developing extrusive igneous rock. Intrusive igneous rock commonly crystallizes at depth of thousands of metres to tens of kilometres listed below the surface. To change its place in the absent cycle, intrusive igneous rock needs to be uplifted and also exposed through the erosion that the overlying rocks.

Through the assorted plate-tectonics-related processes of hill building, all varieties of rocks are uplifted and exposed at the surface. As soon as exposed, they are weathered, both physically (by mechanically breaking of the rock) and chemically (by weathering that the minerals), and also the weathering products — mostly small rock and also mineral fragments — space eroded, transported, and then deposited together sediments. Transportation and also deposition occur through the action of glaciers, streams, waves, wind, and also other agents, and also sediments space deposited in rivers, lakes, deserts, and the ocean.


Exercise 3.1 Rock about the Rock-Cycle clock

Referring to the absent cycle (Figure 3.2), perform the procedures that are necessary to cycle some geological material beginning with a sedimentary rock, which then gets converted right into a metamorphic rock, and eventually a brand-new sedimentary rock.

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A conservative estimate is the each that these measures would take around 20 million year (some might be less, others would be more, and some could be lot more). Just how long could it take for this entire process to be completed?


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Figure 3.4 Cretaceous-aged maritime sandstone overlying mudstone, Gabriola Island, B.C.

Unless they room re-eroded and also moved along, sediments will ultimately be hidden by much more sediments. At depth of hundreds of metres or more, they come to be compressed and also cemented right into sedimentary rock. Again through miscellaneous means, largely resulting from plate-tectonic forces, various kinds the rocks space either uplifted, to be re-eroded, or buried deeper within the crust where they are heated up, squeezed, and changed into metamorphic rock.

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Figure 3.5 Metamorphosed and also folded Triassic-aged limestone, Quadra Island, B.C.