The Geosphere: Earth's Layers, Atmosphere, and Water on Continents

The Geosphere: Earth's Layers

The geosphere https://www.youtube.com/watch?v=FgpGZpVedQsT1. The Earth's layers

1. The Geosphere: the solid part of the Earth
2. The atmosphere: the gaseous part of the Earth
3. The hydrosphere: the liquid part of the Earth
4. The biosphere: the living part of the Earh

Earth's Internal Structure

1.1. The geosphere The Earth's inside is divided into three concentric layers:

a) The crust This is the outermost layer of the Earth. It is very thin, just only a few kilometers. It is solid and is composed by silicates. There are two types of crust:

• Continental crust It makes up the continents. It is thicker than the oceanic crust. The most common rock on it is granite.
• Oceanic crust It makes up the ocean floor. It is thinner than the continental crust. The most common rock on it is basalt.

b) The mantle This is the middle layer. It is situated just below the crust. It is a very thick layer, about 2.900 km thick. It is composed by a rock called peridotite. It is a semi-solid layer and it is divided into two parts:

• The upper mantle
• The lower mantle

c) The core This is the innermost layer. It is situated just below the lower mantle. It the thickest layer, about 3.500 km thick. Its composition is mainly iron. It is divided into two concentric layers:

• The outer core. It is liquid.
• The inner core. It is solid crust 70 km 670 km upper mantle 2 900 km lower mantle outer core 5 120 km inner core 6370 km

Minerals and Rocks

Mineral Characteristics

2. MINERALS The terrestrial crust is formed by different materials. The most important ones are minerals and rocks.

. Minerals: They are substances that have to be:

• Solid at room temperature, that is to say, they cannot be liquids or gases.
• Inorganic, that is to say, they cannot be formed by living beings.
• Defined chemical composition, that is to say, they are formed by one or more elements in a certain proportion that we can express with a chemical formula.
• Natural origin, that is to say, they are not made up by humans.

. Rocks: They are solid substances formed by the combination of minerals.

Reading Activities on Minerals

READING ACTIVITIES After reading the text, copy and answer the following questions into your notebook: Remember: you must make complete sentences.

2.1. Look at the chart and indicate why these substances cannot be considered minerals.

Substance State (at room temperature) Inorganic Chemical composition Natural origin Water Liquid Yes H2O Yes Mercury Liquid Yes Hg Yes Bone Solid No Ca 3(PO4) 2 Yes Plastic Solid Yes Undefined No

2.2. What is the difference between a mineral and a rock? 2.3. Listen and indicate what characteristic of minerals is described: a. Solid b. Inorganic c. Defined chemical composition d. Natural origin

Mineral Examples

abalone ágata MSH 6.5-7.5 SIO, alexandrita amazonita MSH 8.5 BeAI,O, MSH 6 KAISi,O, âmbar MSH 2-2.5 ametista MSH 7 SiO, ametrine MSH 7 andaluzita MSH 7-7.5 apatita MSH 5 água marinha MSH 7.5-8 Be,Al, SiO, aventurina MSH 7 azul mineral MSH 3.5-4 berilo MSH 7.5-8 Be,AĻ SiO, crisocola MSH 2.5-3.5 CuSIO,·nH2O crisópraso MSH 6.5-7.5 SiO, cinábrio MSH 8.1 HgS citrino MSH 7 SIO, diamante MSH 10 esmeralda MSH 7.5-8 Be,AĻ(SIO,), granada MSH 6.5-7.5 Mg,AĻ[SIO,], goshenite MSH 7.5-8 Be AlSIO, hematita MSH 5.5-6.5 Fe,O, jade MSH 6.5-7 NaAl(SiO)) jaspe MSH 6.5-7 SIO, kunzite MSH 6.5-7 LIAISi, O, lapis lazuli MSH 5-5.5 (Na,Ca),AI_Si,O2,(S,SO,) O malaquita MSH 3.5-4 Cu2(CO2)(OH)2 moissanite MSH 9.25 SIC morganite MSH 7.5-8 Be,Al,Si,01, obsidiana MSH 5-5.5 SiO olho de gato MSH 8.5 Al2BeO4

Rock Classification and Formation

Types of Rocks by Origin

3. ROCKS The solid part of the Earth is made up of rocks. Rocks are any natural, inorganic material made up of minerals. Most part of them is compounded by several minerals and is solid. But some rocks are made of a single substance and others can be found in liquid form, for example, oil. According to their origin rocks can be classified as:

. Sedimentary rocks: They are formed by the accumulation and compaction of sediment. These sediments can be:

• fragments of the rocks are carried to where they are them deposited. For example: conglomerate, sandstone, etc
• accumulated chemical substances in the bottom of seas, lakes, etc. For example: gypsum.

· Metamorphic rocks: Forces inside the Earth cause that a rock change into another type, without melting. They are formed from other rocks by the effects of high temperature and pressure.

• due to the high pressure. For example: slate.
• due to the high temperature For example: marble.

· Magmatic (or igneous) rocks: They are formed from cooled magma. Magma is molten rocky material below the Earth's surface. When the magma cools down:

• slowly, inside the terrestrial crust, for example: granite.
• quickly, when it surfaces from volcanoes, for example: basalt.

Rock Types Overview

Types of Rocks Igneous · Forms from magma or lava solidification · Hard, no layers Granite Intrusive slow magma cooling Extrusive rapid lava cooling Obsidian Sedimentary · Forms from sediment compaction · Crumbly, layered Clastic compacted broken rocks Sandstone Chemical compacted dissolved minerals Limestone Organic compacted biogenic matter Coal Metamorphic · Forms by transformation of other rocks · Relatively hard, may or may not have layers Foliated has layers Slate Non-Foliated no layers Marble sciencenotes.org

Sedimentary Rock Formation

b) Formation of sedimentary rocks It begins with the accumulation and consolidation of sediment or of rock fragments. Rocks are fragmented by:

• Weathering. Rocks at the surface of the Earth are broken up by the action of atmospheric phenomena (changes in temperature, rain, etc), or by the activities of plants and animals.
• Erosion. These broken fragments of rocks are swept away by running water, glaciers, waves or wind.

Sediments, minerals and rocks Weathering & Erosion Sedimentation & Deposition Compaction Key Increasing pressure "Cementation" (stuck together)The deposition of sediments in layers, in lakes or seas, takes place over millions of years. The deposited sediments are transformed into compact, cohesive rocks by two processes:

• Compaction. The weight of successive layers of sediment compacts the sediments. This pressure reduces the spaces between the fragments and squeezes out the water. As a result, salt crystals are formed.
• Cementation. The rock fragments are stuck together with the salt crystal which formed when the water was eliminated.

Pressure fragment mineral deposits Deposition of sediments Compaction Cementation

Each layer of sediments is transformed into a layer of sedimentary rock, called a stratum. Organic sedimentary rocks are formed because the rests of vegetation and microscopic marine animals and plants was covered quickly by sediments, avoiding the putrefaction. In this environment, of high pressure and temperature and without air, some kind of bacteria changes the organic matter into coal or oil.

Fossils in Sedimentary Rocks

c) Fossils Sedimentary rocks sometimes contain remains of living things that lived millions of years ago. These remains are called fossils. Fossils become part of the rocks, during the processes of compaction and cementation of sediments. Fossils provide invaluable information about the history of life on Earth.

EXTINCTIONS TON YEARSAGO ERA PERIOD EPOCH O QUATERNARY M.lowvau Pleistocene Mise of Man Plicorce 1.8 Miccene TERTIARY M-T CRETACEOUS Death Race Madora seed bearing plama JURASSIC Fint Birds TRIASSIC 200 Death MISLE TIASSIC Cyrads, Ficat Bindurres 250 PERMIAN Death Rate PFV PERMIAN Fint Reptiles 300 PENNSYLVANIAN rint insects MISISSIPPIAN Mane Criouils DEVONIAN Deech Bara 350 DEVONLAN Tini Swi Flab Cartilage 2uh 400 PALEOZOIC SIELIRIAN Earliest Fand Andinak ORDOVICIAN Desth Ritk Rariy Deny iah 500 CAMBRIAN Bonhioputs, Trilokfica 550 PROTEROZOIC Bacterin. Algae, Jellyfish 1500 ARCHEAN Farthe mist had cooled enough to allow the formation of continente and Hle started to form - 4900 HADEAN Fectoative of the Earth 4540

For a fossil to be considered an index fossil, it has to meet several qualifications:

1. It is easy to identify
2. It lived for a short period of time (in geological terms, on the order of only a few millions of years) allowing scientists to tell time most accurately
3. It is globally distributed - 450 ORDOVICIAN CARBONIFEROUS PHANEROZOIC MESOZOIC Palcacine CENOZOIC

The Rock Cycle Processes

3.4. The rock cycle The rock cycle is a set of processes which form, change and recycle rocks over time. These processes can take thousands or even millions of years. On the Earth's surface, weathering and erosion break down and transport rocks. Under the Earth's surface, rocks go through processes which change them. As a result, they become new rocks. The cycle is continuous.

Weathering, erosion, transport and deposition SEDIMENTS Weathering, erosion, transport and deposition Consolidation and diagenesis Weathering, erosion, transport and deposition Temperature and pressure Temperature and pressure MAGMATIC ROCKS METAMORPHIC ROCKS SEDIMENTARY ROCKS Melting - Cooling and solidification Melting Melting MAGMA

The Hydrosphere

Water Distribution on Earth

The hydrosphere https://www.youtube.com/watch?v=BvrzM-BavDg1. The water on the Earth The Earth is the only planet in the solar system that has surface water: three quarters of the Earth is covered with water. The water on the Earth's surface is called the hydrosphere. Water on the Earth is found mainly in liquid state, but it also exists as ice and water vapour. It is distributed in this way:

• 97 % Oceans and seas. It is salt water.
• 3% Poles, glaciers, lakes, rivers, groundwater, clouds and living beings. It is fresh water.

Origin of the Hydrosphere

a) Origin of the hydrosphere The Earth's hydrosphere has two origins:

• In the primitive Earth there was an intense volcanic activity that released great amounts of water vapour in the primitive atmosphere. This water vapour condensed and became rainfall as the planet slowly cooled down and created the oceans.
• Comets and asteroids entering the Earth's atmosphere also contributed to increase the amount of water in these primitive oceans.

Water Distribution Details

DISTRIBUTION OF WATER ON EARTH Total water on Earth Salt water: 97% Fresh water: 3% Total fresh water Ice: 79% Ground water: 20% Surface fresh water: 1% Total surface fresh water Lakes: 50% Ground: 38% Atmosphere: 10% Rivers: 1% Living beings: 1%