Answer:
Movement in the mantle caused by variations in heat from the core, cause the plates to shift, which can cause earthquakes and volcanic eruptions.
The ruins of two ancient cities, Harappa and Mohenjo-Daro (both in modern-day Pakistan), and the remnants of many other settlements, have revealed great clues to this mystery. Harappa was, in fact, such a rich discovery that the Indus Valley Civilization is also called the Harappan civilization.
Many scholars believe that the collapse of the Indus Valley Civilization was caused by climate change. Some experts believe the drying of the Saraswati River, which began around 1900 BCE, was the main cause for climate change, while others conclude that a great flood struck the area.
The remains of the Indus Valley Civilization cities indicate remarkable organization; there were well-ordered wastewater drainage and trash collection systems, and possibly even public granaries and baths. Most city-dwellers were artisans and merchants grouped together in distinct neighborhoods.
C) one side drops into fault
Similar fossils found on different continents helped geologists determine how the continents used to be connected. Mountain belts marked the boundaries of moving plates, which showed in which direction the different continents drifted. Extrapolating from this information, scientists had a rough idea of how the continents were arranged eons ago.
