Describe and explain the formation of the chain of Hawaiian Islands in the North Pacific Ocean shown in Resource A.

Description: Resource 6A shows a 500km chain of Hawaiian islands in the North Pacific, from the North-west (22oN 160oW) where the islands Niihau and Kauai are located, comprising of rock aged 5.2 and 4.7 million years. Toward the South-east of the chain, the islands of Maui and Hawaii are found, comprising of rock aged 1.5-1.2 and 0.6-0 million years. The resource thus illustrates the positive correlation between the distance away from the island of Hawaii where the only active volcano is found, and the age of geology found on individual islands as well as their size. Explanation: This chain of islands located in the central pacific is the result of a sub-lithospheric thermal anomaly, known as a hotspot. As the oceanic plate moved toward the north-west over time, many submarine volcanoes formed as a result of a fixed plume of heat and magma in the asthenosphere, rising from a hot spot originating deep within the mantle near the edge of the outer core. As the mantle plume rises in the asthenosphere, decompression melting produces magma. This magma rises to erupt at the surface, forming a submarine volcano. These submarine volcanoes may have grown to reach the surface of the sea as a volcanic island. As the oceanic plate continued to move, the volcano is carried further from the fixed hot spot, therefore becoming extinct as it moves away from the source of rising magma. As it moves away, weathering and erosion gradually reduces their size until they are worn down to below sea level, firstly forming platforms for coral reefs to grow on and finally becoming mere stumps of their former size on the seafloor. This process continues in a cycle with the fixed hotspot now under a new piece of pacific crust. This process thus explains the patterns shown in resource 6A, as the islands furthest away from the hot spot (more north-western) are also the oldest in geology and smallest in area. Currently, the only active volcano is found on Hawaii, therefore meaning Hawaii at present above/nearest the hotspot.