Page 40 - Curriculum Visions Dynamic Book. To close the book, close the tab.

Rock cycle
Rock cycle
The continuous sequence of events that causes mountains to be formed, then eroded, before being formed again.
Sediment carried by rivers settles out in inland basins. Some is reworked by the wind. Over time it will be compressed into rock by the weight of fresh sediment accumulating on top of it.
 Rock cycle – The diagram shows how rocks can be eroded and re-deposited where they form as layers and eventually make new rocks. These rocks may then be uplifted to make new mountains.
Rain and ice on mountains weather rock; rivers carry weathered material to lowlands and reduce its size by abrasion and attrition.
Most sediment reaches the sea, where it is reworked by ocean currents. Waves also erode the coast. The sediment finally settles out in layers on the seabed. Over time it will be compressed into rock by the weight of fresh sediment accumulating on top of it.
Some sediment carried by rivers is deposited in river basins as alluvium.
Rock-forming minerals
Although the chemical elements occur in many thousands of minerals, just a few minerals are common in rocks. They are called the rock-forming minerals.
It is important to know about the minerals that form rocks because their hardness, solubility and other properties can help explain why the rock is hard or soft, and how it was formed. The main rock-forming minerals are feldspars, micas, quartz, ferromagnesian minerals, clay minerals, evaporite minerals, calcite and dolomite.
S
Salinisation
The build-up of salt on or near
the surface of a soil. It happens in deserts or near desert areas where soils are not properly irrigated. The
irrigation water (which contains dissolved minerals, including salt) does not drain through the soil, but is pulled back to the surface as the soil dries out.
The process may be accelerated where irrigation water is pumped from an underground supply such as an aquifer that contains a very high dissolved mineral content. When this water evaporates, the minerals are left as deposits in the soil pores or as a crust on the surface.
Salt dome
A balloon-shaped mass of salt produced by salt being forced upwards under pressure. When salt beds are put under pressure, they behave like liquids. If there is a weakness in an overlying rock, the salt will bulge up through the weakness to form a plug or dome- shaped body of salt.
Sand
Particles of rocks with a size between 0.06mm and 2mm. The basis of sandstone rock. (See also: Grain; Grit; Silt.)
40
 Sandstone – Sandstones are made of sand grains cemented together. The dark band in this sandstone is cemented with iron oxide. The lighter bands are cemented with calcite.
Sandstone
A sedimentary rock composed
of cemented sand-sized grains 0.06mm and 2mm in diameter. The nature of the cement affects the hardness and colour of the sandstone. If the cement is calcite, the sandstone is a pale colour
and not particularly resistant to chemical weathering. If the cement is iron oxide, the sandstone