Notes, summaries, assignments, exams, and problems for Geology

Hadean Eon: 4500-4000 Million Years Ago

Geology:

• Intense volcanic activity
• Intense meteorite activity
• Moon formation
• First solid crust
• Formation of mantle and core

Climate:

• Atmosphere formation
• Hydrosphere formation

Archean Eon: 4000-2500 Million Years Ago

Geology:

• First microcontinents (plate tectonics)

Biosphere:

• First prokaryotic cells (bacteria and archaea)

Proterozoic Eon: 2500-541 Million Years Ago

Geology:

• First supercontinent (Rodinia)
• Active tectonic activity

Climate:

• Extreme climates (interior of Rodinia)
• Major glaciation at the end - "Snowball Earth"

Biosphere:

• First eukaryotic cells
• First cyanobacteria - photosynthesis - O2 production
• First multicellular organisms

Phanerozoic Eon: 541 Million Years Ago - Present

Paleozoic Era (541-252 Million Years Ago)

• Cambrian

Sedimentary Rocks

Sedimentary rocks are produced from the weathering of preexisting rocks or biological matter.

• Detrital: Rocks produced from rock fragments.
• Chemical: Rocks produced by the precipitation of dissolved ions in water.
• Organic: Rocks produced by the accumulation of biological debris.

Sediments: Loose, solid particles originating from the weathering and erosion of preexisting rocks.

Deposition: The settling and coming to rest of transported materials and the accumulation of chemical or organic sediments, typically in water.

Lithification: The general term for processes converting loose sediments into sedimentary rock.

• Breccia: Coarse-grained clastic sedimentary rocks.
• Sandstone: Medium-grained clastic sedimentary rock.
• Shale: Fine-grained

Climate Change

Climate Change is the global variation in the Earth's climate. These changes can be caused by processes internal to the Earth, external forces or human activities. However, the influence that our activities have on the planet is called global warming. Because of this, the temperature has increased two degrees in the last thirty years and it will go on increasing in the future if we don't do anything. On the one hand, thousands of people have some responsibility for this change, but on the other hand there are other reasons, as for example: The greenhouse effect, To burn fossil's combustibles, The felling and burning of trees, The pollution that is caused by cars and factories. Some of these activities are giving off so much carbon... Continue reading "The Impact of Climate Change and How to Address It" »

Ozone Depletion

Problem

Ozone hole

The ozone layer

Causes

Chemicals

• Destructive agents: Freon and similar gases used in fridges, air conditioners, aerosols, etc.

Effects

• Skin cancer
• Death of ocean plankton
• Death of crustaceans
• Reduced harvest
• Increased smog
• Destruction of the ozone layer: More ultraviolet rays with an increase in skin cancer

Solutions

Substitution/replacement of these products.

Greenhouse Effect

Problem

Greenhouse effect

Causes

• Chemicals, gases
• Deforestation
• Burning of fossil fuels (coal, oil, peat)

Effects

• Melting of the polar ice caps
• Increase in the world sea level
• Floods
• Changes in the world climate
• Changes in world agriculture
• Droughts (long periods of very dry weather)
• Raising of average temperatures
• Increase in the Earth's global temperature

Solutions

• Reforestation
• Energy

Chapter 7: Volcanoes & Chapter 10: Restless Ocean

Volcanic Eruptions

Eruptions can be explosive (gases escape from melt) or quiescent ("Hawaiian" very fluid basaltic lavas).

Volcano Types

Volcano types include shield volcanoes (accumulation of fluid basaltic lavas, exhibit shape of broad domed structure) and composite volcanoes (large, nearly symmetrical, persistent eruption of viscous lava, conical shape).

Viscosity: Determined by temperature, composition, and amount of dissolved gases – how resistant to flow.

Pyroclastics: Pulverized rock, lava, and glass fragments ejected from vent.

Chapter 9: Oceans

Ocean Features

Continental Shelf: The gently sloping submerged portion of the continental margin that extends from the shoreline to the continental... Continue reading "Volcanoes, Oceans, and Seawater Composition: Key Concepts" »

Speech Sound Classification

Speech sounds can be categorized into vowels, consonants, and approximants. Approximants (glides: /j, w/ and liquids: /l, r/) share characteristics of both vowels and consonants.

Differences between Vowels and Consonants

There are three main differences between vowels and consonants:

1. Articulatory: Vowels are articulated with a stricture of open approximation (no blockage to the airflow). Consonants are articulated with various degrees of stricture:
   • a) Complete -> plosives /p, b, t, d, k, g, ʔ/
   • b) Close approximation -> fricatives /f, v, s, z,.../
   • c) Open approximation -> approximants /j, w, l, r/
2. Acoustic: Vowels are more sonorous than consonants. There are seven levels of sonority: vowels, glides, liquids, nasals,

HUMAN IMPACT

Acidic rain: It is a broad term that includes any form of precipitation with acidic components and results when dioxide (So2) and nitrogen oxides (NO) are emitted into the atmosphere and transported by wind and air currents. Acid rain is caused by the burning of fossil fuels to generate electricity, the chemical releases of vehicles and from manufacturing. There are two forms of acid rain: dry deposition which is crust in a sheltered area and wet depositions that are raindrops of sulphurous acid. Acid rain can be very harmful to the environment because it takes away minerals from the leaves and soil and without them plants cannot grow properly. Even if this rain doesn’t fall straight into lakes it can get there through rivers... Continue reading "Human Impact: Acid Rain, Climate Change, Overfishing, and More" »

EARTH INTERNAL LAYERS: Compositional : Crust (oceanic, continental) Mantle, Core. Phisical: Lithospere (rigid), Low velocity zone (ductile and partially molten), Lower molten (solid), Core (outer molten, inner solid).

 EV OF THE THEORY OF CONT DRIFT: Paleolithic evidence: Fossils. Biological ev: Living beings. Geological ev: Continents fit. Paleoclimatic ev: Glacier rests. BENIOFF ZONE: Area of seismic activity in a subducting plate. WILSON CYCLE: Rift Valley Stage: Magma rises up through fractures making the lithosphere thinner and lower. Red Sea St: Deep lakes are formed at the bottom of the valley, which spreads. Atlantic Ocean st: New oceanic lithosphere is being produced and the Atl Oc is expanding. Pacific Ocean st: The Oc lithosphere... Continue reading "Mnemonic for lithosphere,asthenosphere,mesosphere,outer core and inner core" »

Understanding Plate Tectonics and Earth's Geological Features

Key Concepts in Plate Tectonics

Alfred Wegener

Proposed the theories of continental drift and plate tectonics in 1912.

Continental Drift

The theory that Earth's continents have moved over geological time relative to each other, appearing to drift across the ocean bed; they were once joined together as a single supercontinent.

Plate Tectonics

The scientific theory that the Earth's outer rigid layer, the lithosphere, is broken into large, rigid pieces called tectonic plates that are in constant motion over the Earth's mantle.

Lithosphere

The rigid outer layer of the Earth, consisting of the crust and the uppermost part of the mantle. Tectonic plates are made of the lithosphere.

Asthenosphere

The

Weathering and Erosion

Weathering is the process which causes rocks and minerals to break down and disintegrate into smaller pieces. This can occur through chemical, biological, and mechanical processes influenced by temperature and humidity. Erosion by water forms gullies in the land, which can gradually deepen into ravines and gorges.

Landscapes and Tectonic Plates

Landscapes produced under the surface of the earth are known as karst landscapes. The solid part of the earth is divided into different layers separated by areas known as discontinuities, such as the Mohorovičić discontinuity, Repetti, Gutenberg, and Lehmann. Tectonic plates, made up of the crust and the upper mantle, are massive slabs of solid rock. Volcanoes are cracks or openings... Continue reading "Understanding Weathering, Erosion, and Tectonic Plates" »