1. Continental Drift: The Sahara region was once part of the supercontinent Pangea. Around 200 million years ago, the continents began to drift apart, causing the African plate to move northward. As Africa moved closer to the equator, the climate became hotter and drier.
2. Uplift of the Sahara Platform: Around 70-60 million years ago, the African Plate experienced significant uplift, forming a high plateau known as the Sahara Platform. This upliftment led to the erosion of softer rocks, exposing the more resistant rocks and creating the vast desert plains.
3. Changes in Ocean Currents and Rainfall Patterns: The movement of tectonic plates also influenced ocean currents and atmospheric circulation patterns. The formation of the Atlantic Ocean and the northward movement of the African Plate led to a reduction in rainfall in the Sahara region. This decrease in precipitation further contributed to the drying out of the land.
4. Shifts in the Earth's Axis: Over time, the Earth's axis has experienced slight shifts, causing changes in the distribution of solar radiation. Around 50 million years ago, the Sahara region was positioned closer to the Tropic of Cancer, receiving more direct sunlight. This increased solar radiation led to higher temperatures and further evaporation, reducing rainfall.
5. Expansion of Desertification: The Sahara Desert's expansion can also be attributed to desertification processes. Desertification occurs when non-desert areas become desert due to various factors such as climate change, deforestation, overgrazing, and human activities that disrupt the natural water balance.
These combined factors have contributed to the formation and expansion of the Sahara Desert over millions of years, resulting in the vast, arid landscape we see today.
