<p>Tectonic plates are not single blocks of geology. The <a href="https://en.wikipedia.org/wiki/African_Plate" rel="nofollow noreferrer">Africa Plate</a>, like other tectonic plates, consist of cratons  which are "<strong>stable blocks of old crust with deep roots in the subcontinental lithospheric mantle, and less stable terranes, which came together to form plates</strong>".</p>

<p>The Africa Plates contains the "Kalahari craton, Congo craton, Tanzania craton and West African craton".</p>

<p>The island and volcano of <a href="https://en.wikipedia.org/wiki/Saint_Helena" rel="nofollow noreferrer">St Helena</a>, though on the edge of the Africa Plate, is more associated with the Mid Atlantic Ridge than it is with the Africa Plate.</p>

<p>The cratons and other land masses that form the Africa Plate may be mobile, but St Helena and the Mid Atlantic Ridge are not.</p>

CC BY-SA 3.0
2018-01-23T11:32:30.883Z
It is claimed here that St Helena is more associated with the mid-Atlantic Ridge than the African plate and both are static. However, the island is hundreds of miles from the Ridge and if only the African Plate is mobile, how did the island arrive at its present location? Every reference I have read tells me the island lies on the African Plate and has been steadily moving away from the mid-Atlantic Ridge.
user8654
CC BY-SA 3.0
2018-01-23T08:17:35.857Z
2018-01-23T08:17:35.857Z
Fred
<p>The island of St Helena was volcanically active for five million years or longer. The island is located on the African plate and in that period of time would have moved at least a hundred miles or more. Surely the idea of a single hot spot cannot apply in such a case - it seems more akin to a hot streak. I also wonder whether other mid-oceanic volcanoes were active for similar lengthy periods and whether or not these conform to the idea of single hot spots.</p>

<ocean>
Is the theory of hot spots compatible with lengthy volcanism?
user8654
# Is the theory of hot spots compatible with lengthy volcanism?

(Asked by: username_0 on 2018-01-23)

The island of St Helena was volcanically active for five million years or longer. The island is located on the African plate and in that period of time would have moved at least a hundred miles or more. Surely the idea of a single hot spot cannot apply in such a case - it seems more akin to a hot streak. I also wonder whether other mid-oceanic volcanoes were active for similar lengthy periods and whether or not these conform to the idea of single hot spots.

**Tags:** ocean


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## 1 answers

### Answer by username_1 on 2018-01-23. Score: 2

Tectonic plates are not single blocks of geology. The [Africa Plate](https://en.wikipedia.org/wiki/African_Plate), like other tectonic plates, consist of cratons which are "**stable blocks of old crust with deep roots in the subcontinental lithospheric mantle, and less stable terranes, which came together to form plates**".

The Africa Plates contains the "Kalahari craton, Congo craton, Tanzania craton and West African craton".

The island and volcano of [St Helena](https://en.wikipedia.org/wiki/Saint_Helena), though on the edge of the Africa Plate, is more associated with the Mid Atlantic Ridge than it is with the Africa Plate.

The cratons and other land masses that form the Africa Plate may be mobile, but St Helena and the Mid Atlantic Ridge are not.

> **Comments:**
> **username_0**: It is claimed here that St Helena is more associated with the mid-Atlantic Ridge than the African plate and both are static. However, the island is hundreds of miles from the Ridge and if only the African Plate is mobile, how did the island arrive at its present location? Every reference I have read tells me the island lies on the African Plate and has been steadily moving away from the mid-Atlantic Ridge.  

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