FOSSILS IN THE STREETS OF AMSTERDAM
BLUE LIMESTONE IN ALLEYS AND PAVEMENT - PART I
Left Photo: Natural stone was a popular building material in Amsterdam in the 17th century. Citizens of the Canal District used Belgium greyish 'blue limestone' for outside stairs, façade coverings, roofs of the small annexes to corner houses (so-called 'pothuizen'), doorsteps and pavement.
Right Photo: This Belgium blue limestone is usually very rich in fossils and originates from the Carboniferous, the geological period between 350 and 290 million years ago. The Northern part of Europe, at that time still connected to the American continent, was covered by a vast, tropical sea. The fossil shells, corals and sea lilies we see today in blue limestone are the remnants of this ancient sea life!
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Left Photo: Fragments of sea lilies (crinoids) are very clear on this picture. These five-armed animals (!), now extinct, are related to starfish and attached themselves to the seabed. You either see the arms in a cross-section (circles with a dark core) or at length (like screws). Click here to view the animal in its original state.
Right Photo: Extinct coral colonies in a honeycomb structure, called Michelinia. Hexagonal shapes are quite common in nature. Nature seems to prefer this geometric shape to triangles, squares or other shapes. See also the hexagonal basalt pillars from the Canarian island La Graciosa in the Photo Gallery on this site.
Blue limestone in alleys and pavement - part II
Read the article 'Fossielen op straat' (pdf) 1,2 mb >>
In: Ons Amsterdam, February 2005.
© Annemieke van Roekel, 2005. Niets van deze website mag worden vermenigvuldigd of openbaar gemaakt door middel van druk, microfilm, fotokopie, plaatsing van teksten en/of afbeeldingen op andere websites of op welke wijze dan ook zonder voorafgaande schriftelijke toestemming van de auteur en de betreffende tijdschriftredacties.
Laatste wijziging: 30 juni 2006
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