20
$\begingroup$

I have always wondered what is the origin of Montmartre mountain in Paris. What surprises me is that the whole area seems quite flat, and yet there's a very steep hill in the middle. How has that happen? Is it an instance of some common geological phenomenon?

$\endgroup$
16
$\begingroup$

A clue is in the full name of the hill: 'Butte Montmartre'. A butte is an erosional feature in which a block of resistant rock overlies a less resistant layer. Erosion of the soft layer below causes the more resistant rock to erode as well by undercutting. This can lead to an isolated hill in a relatively flat surrounding.

The Montmartre hill itself consists of relatively resistant sedimentary rocks (can't find what exactly, although Deffontaines (2005) and De Wever (2002) hint at sandstones and shales) overlying soft marls and gypsum, which was mined until 1860, also contributing to instability of the butte (Deffontaines, 2005). Evaporite-diapirism, as mentioned by Spießbürger, might therefore have played a role as well.

Deffontaines, B., B. Fruneau, A. Prunier-Leparmentier, A. Arnaud, R. Cojean, E. Pajot, J. Rudant (2005) Urban instability revealed by DINSAR and SPN Interferometry: The Montmartre "Funiculaire" case example (Paris, France). Géoline 2005
De Wever, P., F. Guillocheau, J. Reynaud, E. Vennin, C. Robin, A. Cornée, D. Rouby (2002) Deux siècles de stratigraphie dans le bassin de Paris. Comptes Rendus Palevol

$\endgroup$
  • $\begingroup$ It would be good to to link the sources from the actual statements in your answer, or at least indicate what they are - "(source)" doesn't give any information. $\endgroup$ – naught101 Apr 17 '14 at 2:31
  • 2
    $\begingroup$ @naught101 I expanded one reference and replaced the other with a more credible source. $\endgroup$ – hugovdberg Apr 17 '14 at 5:55
  • $\begingroup$ And "martre" means "martyr". $\endgroup$ – Quidam Nov 17 at 17:58

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.