This earth cache takes you to the Jardin des Plantes in front of the Saint Samson chapel. This chapel has the particularity of integrating a particular sandstone into its walls: the "roussard". Good discovery !.
saint Samson chapel
This earth cache takes you to the Jardin des Plantes in front of the Saint Samson chapel. This chapel has the particularity of integrating a particular sandstone into its walls: the "roussard". 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 !.
Sandstone is a common detritic sedimentary rock, resulting from the aggregation of sand grains joined by a natural cement. These grains are mainly composed of silica (quartz) but sometimes also grains of feldspar, micas or other materials.
Cementation of the grains is done by precipitation and crystallization of dissolved salts in the water that crosses the sand bed. Gradually, the sand is transformed into solid sedimentary rock. This process is called diagenesis.
Depending on the origin, the location, the evolution of diagenesis, the chemical composition of grains and cement, sandstone will differentiate. Depending on the proportions of sand and cement, it will be more or less friable, dense and resistant to erosion.
Its color - ocher, red, yellow, orange, brown, gray, white - will depend on the composition of the cement. It can be clay, limestone, siliceous, ferruginous, gypsum, bituminous, phosphated ...
Sandstone is a coarse-grained sandstone because the basic material is generally the Cenomanian sand, Cretaceous marine sediment, which outcrops widely around Le Mans. The ocher color which characterizes it is given by the iron oxide present in the cement which concretizes the grains of sand; if the roux pulls in places on the black, it is thanks to oxide of manganese which is added to the oxide of iron to give then a particularly dense sandstone.
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 - Sandstone is called "roussard" because it contains:
- A - gypsum
- B - clay
- C - iron oxides
- Q2 - By helping you with the explanations above, what rubble hidden in red on the photo is roussard sandstone ? . Explain how you recognized it?
- 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 email@example.com or via geocaching.com messaging (Message Center), and I will contact you in case of problems." BON GEOCACHING!
To valid your visit: