Charles Darwin geologist at Santiago (Cape Verde islands): a field reappraisal

 

Su iniziativa della Associazione Ardito Desio, e con la sponsorizzazione di diversi Enti e Istituzioni, fra i quali l'INGV, una serie di spedizioni sull'Isola di Capo Verde ha ripercorso i luoghi e le formazioni geologiche visitati e descritte da Charles Darwin durante il suo viaggio di naturalista intorno al mondo.
Questo seminario confronterà i concetti geologici usati da Darwin con quello che vedremmo oggi noi sulle stesse rocce.


AUTORI: Giorgio Pasquarè 1· Guido Chiesura 2· Teodoro Aldo Battaglia 2
Ilaria Guaraldi Vinassa de Regny 3· Federico Pezzotta 3

1. Università degli Studi, Milano
2. Soil S.r.l., Milano
3. Museo Civico di Storia Naturale, Milano

ABSTRACT:
Darwin’s visit to the island of Santiago of Cape Verde as first stop of his journey around the world had a fundamental role for the maturation of his interest for Geology, a science that he considered to be his main research subject in the naturalistic field. In the 180 years that separate us from this event, no geologist has ever followed Darwin’s footsteps to reconstruct the objectives, the methods and the results of his research on the island. Quotations found on biographical or historical texts are the only traces left of it, while in geological literature Darwin’s contribution to Santiago’s geology is almost completely absent. Also as a consequence of that, even in more recent works, same faults appear about the geomorphology and stratigraphy of the southern part of the island. The objective
of this work is therefore to fill these gaps by means of a field revision of Darwin’s geological observations, their interpretation and completion, taking into consideration the knowledge, the methodology and the opportunities offered by his time.
The present work is dedicated to the memory of Fabrizio Innocenti, who masterfully conciliated the objectivity of scientific observation and his profoundly
religious soul. The article presents the reconstruction and revision of the geological observations made by Charles Darwin at Santiago of Cape Verde on the first leg of circumnavigation of the globe he completed under the title of «Naturalist», on board the bark «Beagle» of the British Navy. The first true geological experience of Charles Darwin has a significance that transcends the specific episode. On his own admission, the three weeks passed on the arid ground of the Island of Santiago made of Darwin a geologist and of that geologist an author of scientific theories and geological texts. Our exercise thus had the specific idea of visiting areas and their geological structures (Fig. 1) that would see the young Darwin engaged in explaining the outcomes which the science of that day allowed him, along with the perplexities and limitations thereby entailed, to read his campaign notes taking into account the level of knowledge and the conditioning of the epoch.
With this work it is our intention to offer a geologists’ tribute, perhaps modest but impassioned, to the first reflections of that genius who became a geologist right
from the start of his scientific activities and remained assuch ever after. A tribute due also because in the almost one hundred and eighty years dividing us from that occasion, only Pearson and Nicholas (2007) have revisited in person Darwin’s work on Santiago of Cape Verde. Their work consisted moreover in an eminently historic investigation, in which the authors deal only with those aspects of Darwin’s research useful to maintain that at Santiago he may have been far from abandoning catastrophism in favour of gradualism and that his Lyellian ‘conversion’ might have been very gradual during the further course of his voyage and certainly not effected while he was staying at Cape Verde.




Keywords: Darwin, «Beagle», Mantle Plume, Elevation Craters, Basaltic Lava Flows