The 3 limestone of garden
TWhile walking through the garden of the plants you will discover 3 types of limestone of different age:
Earthcache reminder: There is no container to search for and no logbook to fill out. You just have to go to the scene and make the observations. Good discovery !
The tufa; 90 million years ago, Mesozoic (secondary era), Cretaceous,
Oolitic limestone,; 170 million years Mesozoic, Jurassic, Pliensbachian stage
gray limestone; 370 million years, Paleozoic (primary era), Devonian .
The tufa is a calcareous rock that was formed from a loose mud and waterlogged, which then gradually and slowly transform into rock, especially under the effect of pressure, forming benches up to 40 m thick. It is a sandy chalk with fine grain, white or sometimes yellowish cream color..
The oolitic limestone found here probably comes from the Durtal region. (near Angers) The rock is composed of small juxtaposed balls called oolites, Oolites are small, regular spherical mineral structures (ooid) formed, during a particular process of sedimentation, embedded in a limestone cement. It can come from:
- debris of biological origin
- small fragment of rock debris
- a solubilized carbonate grain
Oolitic l had been formed in a shallow but agitated marine environment
Gray limestone is of Devonian age and of reef origin.
These limestones were constrained during the formation of the Hercynian chain (middle of the primary era). These stresses induce folds, faults and diaclases (fractures without displacement) in the rocks. These fractures are often underlined by calcite veins; a mineral recognizable by its clear crystals and hues.
To validate your visit to the site, send us, specifying the name of the earthcache, your answers by e-mail (from our profile, or on the e-mail of geocaching.com) to the following questions. You can log in "Found it". We will contact you if necessary.
Q1: try to recognize the limestone rocks hidden under the red caches by giving the clues that allowed you to recognize them: sight and touch.
Q2: Concerning the oolitic limestone give the diameter of the oolites,
Q3: For gray limestone, is it veined with calcite or not?
WPA washbasin N47 ° 28.515 W000 ° 32.633
WPB chapel N47 ° 28.534 W000 ° 32.715
WPC the bust: N47 ° 28.527 W000 ° 32.681
- Do not attach photos that may reveal answers to the questions above;
Reminder concerning "Earthcaches" There is no container to seek or of logbook to learn. Simply visit the site and make comments."log the cache" Found it "and send me your answers proposals either to firstname.lastname@example.org or via geocaching.com messaging (Message Center), and I will contact you in case of problems." BON GEOCACHING!