Geological Eras: A Journey Through Time
Precambrian Era
The Precambrian era is characterized by the formation of crystalline basement rocks, which are the foundations of future continents. Glacial moraines indicate that the Canadian and Baltic masses were covered by an ice sheet. The era saw the emergence of chemical compounds, including organic compounds, which led to the formation of elementary bodies. The raw materials for processing would be the gases of the atmosphere (methane and ammonia) coupled with large shocks and radiation from lack of oxygen. Calcareous algae appeared, and the photosynthetic capacity of algae led to a better atmosphere. Invertebrate organisms appeared at the end of this period.
Primary or Paleozoic Era
Two major orogenies (Caledonian and Hercynian) occurred. The Caledonian occurred in the Silurian, and the other in the Carboniferous and Permian. This distributed the lands into three land masses: North Atlantic continent (Europe, N. America and Greenland), Chinese-Siberian continent (Asia), and Gondwana (America S. Africa, Madagascar and Australia). These are separated by two geosynclines (Urals and Tetris). The continents’ materials are metamorphic rocks (lava), and highlight the slate and quartzite (granite). The presence of coral reefs indicates a mild and humid climate. Forests extended in the Carboniferous and Permian periods. Calcareous algae appeared first, and plants appeared after in the Carboniferous, where vast forests of sigillarias developed. During the Permian, conifers (pines) appeared. Animals included marine invertebrates such as sponges and crustaceans (trilobites are typical). Amphibians appeared in the Devonian and Carboniferous, with a transition to reptiles.
Secondary or Mesozoic Era
Gondwana began to break before it was created. In the Jurassic, there was a marine transgression in Europe, and it became an archipelago (islands of the Iberian plateau, Scotland, Ireland, England, and the French Massif Central). The Alpine Orogeny began in the tertiary sector. The climate became more uniform from the Triassic. The end of the era saw a cooling. Araucaria trees (plants without flowers) predominated, and flowering plants (angiosperms) appeared, including eucalypts, willows, and palms. This was the age of reptiles, and vertebrates appeared. The first birds appeared.
Tertiary Era
Alpine movements shaped the current distribution. The era is linked to the mainland Greenland North Atlantic. Europe and Asia are separated by sea (they were the Urals). The Strait of Gibraltar did not appear until late Tertiary. There was a steady fall in temperature from the middle of the era. The Quaternary ice ages began. Development of angiosperms occurred, and deciduous forests and flat sheets appeared. Saurian reptiles disappeared, and mammals were followed by placenta and large vertebrates.
Quaternary Era
Changes occurred that strengthened the era, though they were short. There was a process of modeling land left in its current form with the glacial climate changes, the appearance of man, glaciations, and interglacial periods. The following are the glacial periods: 1st 600,000-540,000 GUNZ, 540,000-480,000 PI-G, 480,000-430,000 MINDEL, 2nd IP, 430,000-240,000 M, 3rd 240,000-180,000 RISS, RISS, 180,000-120,000 PI-Wurm, 12,000-10,000 WURM. After this comes the Neolithic (until now was the Paleolithic) and works the land.
Time Period
- Archean
- Precambrian (Archean and Algonquin)
- Paleozoic
- Cambrian
- Silurian
- Devonian
- Carboniferous
- Permian
- Mesozoic
- Triassic
- Jurassic
- Cretaceous
- Tertiary
- Quaternary (Neogene)