Tidal force
Topic: Continental Drift, Sea-floor Spreading and Plate Tectonics · NCERT: Class 11, Ch 4 "Distribution of Oceans and Continents"
Meaning
The tidal force was the second force Wegener proposed to explain continental drift. It comes from the pull of the moon and the sun, the same pull that raises ocean tides. Wegener thought it would slowly move continents westward if it acted over millions of years. Scientists judged it totally inadequate, because a force strong enough to move continents would have stopped the earth's rotation. With no workable force, drift was largely rejected until ideas such as Holmes' convection currents came along.
Example
The rise and fall of tides on India's west coast, such as in the Gulf of Khambhat in Gujarat, comes from this pull of the moon and sun. Wegener wrongly thought the same pull could drag whole continents westward.
Don't confuse with
- Pole-fleeing force: The pole-fleeing force comes from the earth's rotation and was meant to push continents towards the equator. The tidal force was meant to push them westward.
- Convection currents: Convection currents are slow movements of hot rock in the mantle, proposed by Arthur Holmes. This is the force accepted today, unlike the tidal force.