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The Daily Volcano Quote: Darwin on volcanic islands 17 February 2009

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St. Louis, Mauritius.

It is singular in how many respects those portions of St. Jago and of Mauritius which I visited, agree in their geological history. At both islands, mountains of similar external form, stratification, and (at least in their upper beds) composition, follow in a curved chain the coast-line. These mountains in each case appear originally to have formed parts of one continuous mass. The basaltic strata of which they are composed, from their compact and crystalline structure, seem, when contrasted with the neighbouring basaltic streams of subaërial formation, to have flowed beneath the pressure of the sea, and to have been subsequently elevated. We may suppose that the wide breaches between the mountains, were in both cases worn by the waves, during their gradual elevation,—of which process, within recent times, there is abundant evidence on the coast-land of both islands. At both, vast streams of more recent basaltic lavas have flowed from the interior of the island, round and between the ancient basaltic hills; at both, moreover, recent cones of eruption are scattered around the circumference of the island; but at neither have eruptions taken place within the period of history. As remarked in the last chapter, it is probable that these ancient basaltic mountains, which resemble (at least in many respects) the basal and disturbed remnants of two gigantic volcanos, owe their present form, structure, and position, to the action of similar causes.

This excerpt from Geological Observations on the Volcanic Islands visited during the Voyage of H.M.S. Beagle (1844) is quite simply a wonderful example of Charles Darwin’s gifts of observation, theorization and imagination at work on the interpretation of landforms, not merely as they exist in space, but as they have come into being through time.

From Charles Darwin, Geological Observations on the Volcanic Islands visited during the Voyage of H.M.S. Beagle (London: Smith, Elder, 1844), p.31. Available online at The Complete Work of Charles Darwin Online.

For one week from 12 February 2009, the 200th anniversary of Charles Darwin’s birth, The Volcanism Blog will feature a volcano-related quote from Darwin each day.

The Daily Volcano Quote: from Monday to Friday, a new eruption of volcanic verbiage each day.

The Volcanism Blog


1. The Bobs - 17 February 2009

I’ve been to Mauritius, but what is St. Jago?

2. volcanism - 18 February 2009

‘St Jago’ is the island of São Tiago in the Cape Verde Islands.

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