THE LITHOSPHERE • Approximately100 km thick • The outer shell is made up of the Earth’s crust and the top part of upper mantle • It contains minerals & rocks
1.1 MINERALS Inorganic, neither animal nor plant; found in nature; for most, atoms are organized in a set pattern (ex. salt crystals), fig. 6.2 (p.185); elements (ex. Au - gold) or compounds (ex. Cu SO4 - copper sulfate); 4000+ different minerals; common: feldspar, quartz, mica…; rare (precious): diamonds, rubies, emeralds…
DO NOT MEMORIZE • MINERAL CLASSIFIACTION • They are classified according to the following properties: • Idiochromaticminerals - have a characteristic color • Allochromatic minerals - color varies; would be colorless but diverse impurities add different colors, ex. Quartz • Transparency: degree to which light passes through; 3 levels, from complete to none: • 1)Transparent (ex. rock crystal, regular glass) • 2) Translucent (ex. olivine, frosted glass) 3) Opaque (ex. pyrite, solid black plastic)
- HARDNESS: dependent on bond strength of atoms • Mohs scale indicates hardness • 1(very soft; easily scratched by nail; ex. talc) • 10(very hard; can scratch all others; ex. diamond) - a higher level (ex. quartz: 7) can scratch all levels lower than itself, i.e. levels 1-6 - hardness is important for jewelers, for cutting and polishing DO NOT MEMORIZE
STREAK: • Amark left by a mineral on a slab of unglazed porcelain; a char. of minerals; idiochromatic minerals leave brightly colored streaks/powder; allochromatic minerals leave white /pale streaks DO NOT MEMORIZE
DO NOT MEMORIZE • MINING - Ore: the material (rock) extracted from the lithosphere; contains a desired mineral - Deposit: site that contains a high concentration of a certain mineral • Qc has Au, Cu, Zn, Ni, and Fe deposits; most active region: Abitibi-Témiscamingue • region (Rouyn-Noranda), fig. 6.8 (p.187) - Mining: complex; costly; Open-pit mine: if deposit is near surface; if deposit is too deep: underground passages, including a huge vertical shaft, drifts (horizontal tunnels, air ducts, & water supply lines) must be built
1.2 ROCKS Rocks are heterogeneous solids composed of more than one mineral • There are three types: • IGNEOUS: made of cooled lava There are two types: a) EXTRUSIVE: lava cools when it comes in contact with air; ex. rhyolite, obsidian, basalt b) INTRUSIVE: magma solidifies underground; ex. granite, basalt (occurs both ways) (2) SEDIMENTARY: the erosion of plant and animal debris falls into water forming layers that compact over time; ex. evaporates, sandstone, limestone, shale (3) METAMORPHIC: igneous/sedimentary rocks change when subjected to high temperatures and pressure; ex. limestone can change into marble, granite into gneiss, shale into slate, jadeite-rock usages table 6.15 (p.191)
Formation of igneous rocks Volcano Formation of igneous extrusive rocks Magma intrusion Igneous rocks form from magma Magma Formation of igneous intrusive rocks
Pumice rock is a type of extrusive rock. It is magma that cooled quickly while being thrown into the air during a volcanic eruption. This rock contains so many bubbles of air that its density is lower that water. It floats when placed in water.
Obsidian is an igneous extrusive rock that has a glossy structure. Rhyolite is an igneous extrusive rock that has a fine grain structure.
Gabbro is an example that shows many different colours of minerals. Diorite is similar to gabbro, but its colours are lighter.
1.3 SOIL Originates from the PARENT ROCK which is part of the Earth’s crust; soil is made up of SOIL HORIZONS, parallel and horizontal layers which are represented by capital letters in the diagram right; fig. 6.16 (p.192); notice how color darkens as more organic matter is present - soil formation takes ~ 200 years!
Steps & Layers: • PARENT ROCK is stressed by frost, wind, & rain. (2) The parent rock becomes the LITHOSOIL which is made up of large pieces of disintegrating parent rock; light colored and coarse. Lithosoil is mixed with humus (organic matter from decaying plant & animal matter) (3) Thelithosoilproduces a series of physical & chemical reactions that lead to the formation of SUBSOIL (small mineral particles, tree roots tips, darker & pieces of rock become smaller) (4) TOPSOIL is made of darker, humus rich, light, air pockets, water soluble minerals, plant roots which can sustain plant life. (5) ORGANIC MATTER is the most superficial layer and it is mostly humus - the more humus a layer has, the more nutrients and small organisms it will contain - to be able to sustain life, soil must contain: asufficient amount of minerals, moistureand an adequate pH level that promotes mineral absorption
HUMUS, organic matter that has decayed to a relatively stable, amorphous state. Humus is formed by the decomposing action of soil microorganisms (e.g., bacteria and fungi), which break down animal and vegetable material into elements that can be used by growing plants. Because of its low specific weight and high surface area, humus has a profound effect upon the physical properties of mineral soils with regard to improved soil structure.
Degradation of the mother-earth Parent-earth From left to right, we can see the evolution of the soil: the main ground floor (Mother-earth) begins to gradually degrade.
BUFFERING CAPACITY: is the ability to withstand changes in pH when acidic/alkaline substances are added to the topsoil - Plants prefer pH levels between 6 & 7; conifersprefer more acidic soil - A soil can neutralize (buffer) itself to a certain point, this protects it from changes in pH - best buffer: fine soil components, ex. organic matter & clay
1.4 PERMAFROST Soil that has been solid for more than two years; 50% of Canada’s land; up to 500 m deep; it is found in polar regions or higher in altitude; top layer can thaw in summer (active layer); agriculture is impossible and construction difficult since permafrost softens easily if temperature rises.
1.5 ENERGY RESOURCES • FOSSIL FUELS: coal, natural gas and oil; they come from the transformation of organic residue. - Oil: originates from dead marine animal and algae that sank to the ocean floor & transformed to oil over time as the pressure of upper layers caused the change; fig. 6.22 (p.196); considered nonrenewable since millions of years are needed for its formation.
Coal: originates from terrestrial plant and trees that grew in swamps; plant debris became covered by layers of sand and silt which continued to accumulate over time, the pressure of which compressed the residues to coal (solid) - Burning fossil fuels emits thermal ener. (from chemical bond breakage) which is converted into electrical or mechanical ener.; combustion causes greenhouse gases & acid rain
URANIUM: naturally occurring in Earth’s crust; radioactive element; nuclear ener. is produced when the nucleus is split releasing ener. stored by nuclear particles; nuclear ener. can be converted to electricity • greenhouse gases not produced during nuclear ener. formation, rather produces heat & radioactivity (a serious health risk) • even if nuclear reactors are encased in reinforced concrete, accidents & leaks can still occur • nuclear waste also produced & no neutralization methods exist; waste is cooled & buried in special pits or old mines - in Qc only 1 nuclear plant: Gentilly-2 in Bécancour near Trois-Rivières