HKDSE Geography/M1/Continental-Continental Destructive Plate Boundaries

When two continental crusts collide, neither crust is subducted as they are of roughly equal density. This collision is found along the Alpine-Himalayan Belt, where the Indo-Australian, Arabian and African plates collide with the Eurasian Plate.

The World's Destructive Plate Boundaries

Circum-Pacific Belt	Pacific	North American|
		The Philippines	Eurasian
		Indo-Australian
		Eurasian
	Cocos	Caribbean	South American
		Nazca	South American
Alpine-Himalayan Belt	African	Eurasian
	Arabian
	Indo-Australian

The Himalayas (Indo-Australian + Eurasian)

Note: This chapter involves a lot of processes. All of them must be memorised. For longer sentences, the important keywords will be underlined to facilitate memory.

1. Converging/sinking magma currents between the Indo-Australian and Eurasian plates cause the two plates to converge with each other under compressional force, forming a destructive plate boundary
2. Denser, thinner, basaltic oceanic crust from the Indo-Australian Plate is subducted under lighter, thicker continental crust from the Eurasian Plate
3. Sediments are washed ashore on the Eurasian plate
4. As the plates converge, water is squeezed out and the sediments are compacted to form sedimentary rock
5. The continental crust of the Indo-Australian and Eurasian plates are equally light and neither can subduct under the other
6. The sedimentary rocks are compressed to form a fold mountain range, the Himalayas.

Hazards in the Himalayas Various HKCEE MC questions throughout the years have confirmed that the Himalayas sometimes experience earthquakes, but rarely experience volcanic eruptions.