Biogeography

Alexey Shipunov

Minot State University

Lecture 6

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Outline

Basics of physical geographyBasics of climatology

PalaeogeographyGeological timePlate tectonics

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Outline

Basics of physical geographyBasics of climatology

PalaeogeographyGeological timePlate tectonics

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Basics of physical geography Basics of climatology

Basics of physical geographyBasics of climatology

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Basics of physical geography Basics of climatology

Holdridge life zones

3 axes: biotemperature, PET (how much water would be evaporated ifavailable) and precipitation. Intersections of all three give life zones.

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Palaeogeography Geological time

PalaeogeographyGeological time

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Palaeogeography Geological time

Use of radioactivity

I In 1896, Becquerel discovered radioactivity. It was found thatsome atoms are constantly breaking into smaller ones, sometimeswith very slow speed

I Consequently, it is possible can calculate the age of mineral fromthe concentration of radioactive elements

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Palaeogeography Geological time

Stratigraphy

I Upper layers are younger than lowerI Two layers contained similar species of fossils have the same time

of origin

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Palaeogeography Geological time

How stratigraphy works

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Palaeogeography Geological time

Stratigraphy and radioactivity work together

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Palaeogeography Geological time

Geological scale

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Palaeogeography Geological time

Geological scale (variant 2)

I want you to memorize eras and Mesozoic/Cenozoic periods.

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Palaeogeography Plate tectonics

PalaeogeographyPlate tectonics

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Palaeogeography Plate tectonics

Continental drift

I In 1921, Alfred Vegener invented the idea that South America andAfrica were parts of one big continent—Gondwana.

I According to Vegener, in the end of Paleozoic era, there were twobig continents—Gondwana and Laurasia separated by Tethysocean

I Before that, all continents were united in one—Pangaeasurrounded by one big ocean.

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Palaeogeography Plate tectonics

One of Vegener’s arguments

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Palaeogeography Plate tectonics

Laurasia and Gondwana

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Palaeogeography Plate tectonics

Pangaea

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Palaeogeography Plate tectonics

Mantle convection

I The driving force of floating continents is a mantle convectionI In ocean ridges, new ocean cortex is constantly forming and

expandingI In ocean trenches and continental ridges, different plates are

colliding and often forming mountains

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Palaeogeography Plate tectonics

Summary

I Geological time is calculated on the basis of both relative(stratigraphy) and absolute (radioactivity) methods

I Continents of Earth are constantly changing their position due tothe mantle convection (“plate tectonics”)

I In the past (Permian period) all continents formed super-continentPangaea, which then broke into Laurasia and Gondwana

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Palaeogeography Plate tectonics

Mantle convection

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Palaeogeography Plate tectonics

For Further Reading

A. Shipunov.Biogeography [Electronic resource].2014—onwards.Mode of access:http://ashipunov.info/shipunov/school/biol_330

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