What landforms and associated tectonic phenomena are found at plate boundaries?

Question 1

Fold mountains

Answer 1

. Formed along convergent plate boundaries
. When plates move towards each other and collide, the resultant compressional forces create immense pressure
. This causes the layers of rocks to buckle and fold.
. This process is called folding.
. Upfold is called anticline and downfold is called syncline

Question 2

Locations of fold mountains

Answer 2

. can be found at convergent plate boundaries
. can be convergence of two continental plates or a continental plate and an oceanic plate.
. Eg: Himalayas and Rocky Mountains
. Himalayas and the Rocky Mountains are considered geologically young fold mountains as they are less than 100 million years old
. Young fold mountains are located along the active plate boundaries and are still growing taller
. Old fold mountains like the Appalachian Mountains in the United States of America and the Ural Mountains in Russia were formed about 270 million to 400 million years ago.

Question 3

Himalayas

Answer 3

. Earth’s highest mountain range, the Himalayas, which span 2,500 km across southern Asia.
- was formed when the northward-drifting continental Indian plate collided with the continental Eurasian Plate.
- both continental plates resist subduction, causing the layers of rocks to be compressed together.
- layers of rocks buckle and fold, forming the Himalayan fold mountains
- collision also led to the elevation of the Earth’s tallest and largest plateau, the Tibetan Plateau.

Question 4

The Rocky Mountains

Answer 4

. located in North America
. created when the denser oceanic Juan de Fuca Plate almost completely subducted beneath the less dense continental North American Plate.
. continental plate buckles and folds, forming the Rocky mountains.

Question 5

Rift valleys

Answer 5

. formed at divergent plate boundaries
. when plates are pulled apart, parts of the crust are fractured and displaced
. this process is called faulting
. result of tensional forces on continental plates
. results in faults, which are fractures in rocks along which rocks are displaced
. along these faults, sections of the crust can extend
. when the sections of the crust extend along fault lines, tensional forces can cause the central block of land to subside between a pair of parallel faults, forming a rift valley.

Question 6

Block mountains

Answer 6

. tensional forces can produce block mountains
. block of land with steep slopes left standing higher than the surrounding land
. when tensional forces cause land masses surrounding the block of land to subside, a block mountain is formed between a pair of parallel faults

Question 7

Locations of rift valleys and block mountains

Answer 7

. Rift valleys and block mountains are found at divergent plate boundaries
. Eg 1: East African Rift Valley
. formed when Somalian section of the African Plate diverged from the Nubian section of the African Plate
. Some of the deep valleys within the East African Rift Valley have been filled with water, resulting in lakes
. Eg 2: Hutt Valley of New Zealand
. formed by the divergence of the Australian Plate and the Pacific Plate
. Eg 3: the Vosges in France and the Black Forest in Germany
. formed by the divergence of the Eurasian Plate and the North American Plate
. separated by the Rhine Valley