What is the origin of the Montmartre mountain in Paris?

Question

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?

Answer 1

Montmartre’s steep hill is the result of geological resistance: harder limestone layers resisted erosion while surrounding softer sediments wore away, leaving the hill as a remnant high point. Montmartre, rising about 130 meters (430 feet) above the surrounding landscape, stands out dramatically in the otherwise relatively flat Parisian basin. Its origin is tied to the geological structure of the Paris Basin, which consists of layered sedimentary rocks deposited over millions of years.

Montmartre is not a mountain, but a butte—a steep-sided hill formed by differential erosion. The hill is composed primarily of Lutetian limestone, a hard, compact rock formed during the Eocene epoch (~45 million years ago). Surrounding areas consist of softer marls and clays, which erode more easily under the influence of wind, rain, and river activity.