 |
Heat plumes at boundary between the Earth's
metal core and it's rocky mantle 1,800 miles below ground.
Lawrence Berkeley National Laboratory
University of California, Berkeley |
This visualization of the plumes of hot rock rising through the mantle correlate to hotspots around the planet where we observe the ongoing generation of chains of volcanic islands.
Geologists have long recognized the ongoing occurrences of terrestrial changes as Sir Archibald Geikie observed in his 1879 lecture to the Royal Geographical Society:
Looking back across the long cycles of change through which the land has been shaped into its present form, let us realise that these geographical revolutions are not events wholly of the dim past, but that they are still in progress. So slow and measured has been their march, that even from the earliest times of human history they seem hardly to have advanced at all. But none the less are they surely and steadily transpiring around us. In the fall of rain and the flow of rivers, in the bubble of springs and the silence of frost, in the quiet creep of glaciers and the tumultuous rush of ocean waves, in the tremor of the earthquake and the outburst of the volcano, we may recognise the same play of terrestrial forces by which the framework of the continents has been step by step evolved.Structural Cutaway
— Sir Archibald Geikie, lecture at the RGS, 24 March 1879
 |
| source: kelvinsong |
Earth's crust consists of oceans and continents.
Underlying the crust is the mantle which is about 1,800 miles thick.
The mantle consists of hot but solid rock. Below the mantle is the outer core which is a liquid layer of molten iron and nickel.
And many a fire there burns beneath the ground.
— Empedocles
— Empedocles
The inner core is solid iron.
Terrestrial Change
Heated by the hot core, rock in the mantle rises and falls. Plumes of hot rock occasionally penetrate the crust to produce volcanoes. As Earth's crust moves laterally around the planet via plate tectonics, the hot stationary rock in the mantle penetrate the crust to generate chains of islands.
The Galapagos, Cape Verde, Samoa, Hawaiian, and Canary islands are examples of volcanic island chains created by Earth's crust moving laterally over stationary super-heated mantle rock.
REFERENCES
- CT scan of Earth links deep mantle plumes with volcanic hotspots, Science Daily, 2 September 2015.
- Structure of the Earth, Wikipedia.
- Today in Science quotations.
