Earth’s Geological Timeline: From Hadean to Today
Earth’s Geological Timeline: 4.65 Billion Years of History
Geological Time Divisions
Earth’s existence spans approximately 4,650 million years (Ma). The largest unit of geological time is the eon. There are two great eons:
- Precambrian: Comprises 90% of Earth’s history.
- Phanerozoic: Divided into three eras: Paleozoic, Mesozoic, and Cenozoic.
These eras are further divided into periods. The Cenozoic era, for instance, is divided into the Tertiary and Quaternary periods.
Hadean Period: The First 500 Million
Read MoreUnderstanding Natural Hazards and Disaster Risk Reduction
Natural Hazards and Their Impact
Natural hazards are the probability of harmful consequences occurring due to physical phenomena motivated by natural forces: hydrological, geological, or atmospheric. These events can lead to disaster. They are not only a cause of death but are also usually accompanied by disease, famine, and poor drinking water supply. In many cases, the affected areas are located in underdeveloped countries, where infrastructure and measures to prevent disasters are scarce or nonexistent
Read MoreMineralogy: Understanding Minerals and Their Properties
Introduction
Mineralogy is the science responsible for the identification of cation minerals. It studies their properties, origin, and classification.
Minerals are bodies of solid matter in the soil that can appear in diverse forms, either isolated or as a fundamental component of rocks.
Minerals
A mineral is a natural, homogeneous substance of inorganic origin, chemically defined (within certain limits). It has specific properties and characteristics and generally has a crystalline structure.
Characteristics
Read MoreUnderstanding Geothermal Gradients, Volcanoes, and Eruptions
Understanding Geothermal Gradients and Volcanic Activity
1. What is the Geothermal Gradient?
The geothermal gradient refers to the increase in temperature with depth beneath the Earth’s surface.
2. Origin of Earth’s Internal Energy
The Earth’s internal energy is believed to originate from two primary sources:
- Primary Energy: Residual heat from the Earth’s formation, due to collisions with other celestial bodies.
- Radioactive Decay: Heat generated by the decay of radioactive elements abundant in the Earth’
Water, Minerals, Rocks, and Matter Properties
Unit 9: Water and the Hydrosphere
Groundwater
- 97% Saltwater
- 3% Freshwater
Ocean water has three types of movements: waves, currents, and tides.
Freshwater can be found in various forms: lakes, rivers, streams, groundwater, wetlands, and glaciers.
Water Cycle
- Evaporation: Water (Liquid) > Gas. Hydrosphere > Atmosphere.
- Condensation: Water (Gas) > Liquid. Forms dew and clouds, which can cause precipitation.
- Runoff: Surface water movement through the earth’s surface, forming rivers and streams.
- Infiltration:
Volcanic Structures, Activity Types, and Landforms
Volcanic Relief
Structure of a Volcano
- Crater: Orifice where volcanic products exit the surface.
- Volcanic Cone: Structure formed by the accumulation of volcanic material around the crater.
- Chimney: Tube that connects the magma chamber to the crater, where the magma exits.
- Magma Chamber: Deposit in which magma accumulates before going outside.
Volcano Types
Depending on the characteristics of the material ejected, volcanoes have different types of structures:
- Pyroclastic Cone: Small, with very steep walls,