Les calcaires oolithiques : La Grande Oolithe est un calcaire composé de sphérules de teinte bicolore, beige et bleu. C'est la pierre de taille principale dans la boucle. Ces calcaires sont d'âge Bajocien supé- rieur (171 à 169 Ma).
Les calcaires micritiques: Calcaires microcristallins (ou micritiques) et graveleux (quicontiennent des graviers) de teintes blanche et beige. Ces calcaires sont d'âge Bathonien (167 à 164 Ma).
Les constructions de la ville les plus anciennes (vestiges gallo-romains notamment) sont réalisées en calcaire de type Vergenne qui est
un calcaire oolithique. Ce calcaire blanc, assez tendre se travaillait plus facilement que la Grande Oolithe et résiste mieux au gel. Ce calcaire provient de carrières situées soit à Charcenne (Haute-Saône), soit sur les hauteurs dominants Cléron (Doubs), soit proches de Mandeure (Nord du Doubs). Les architectes de cette époque n'hésitaient pas à priviligier la qualité de la pierre au détriment du transport, compte tenu de l'abon- dance de matériaux calcaires locaux. (sources: Nicolas Carry)
Rappel: pour les earthcache, il n'y a pas de cache à trouver, il suffit de répondre aux questions suivantes, donc: "loguez cette cache "Found it" et envoyez-moi vos propositions de réponses soit via mon profil, soit via la messagerie geocaching.com (Message Center), et je vous contacterai en cas de problème."
1- Indiquez au waypoint 1, quels monuments (1) sont visibles et de quelle(s) pierre(s) calcaire oolitihique ils sont composés : Vergenne, Micritique, Oolithique ou à entroques./p>
2- Indiquez au waypoint 2, quels monuments (2) sont visibles et de quelle(s) pierre(s) calcaire oolitihique ils sont composés : Vergenne, Micritique, Oolithique ou à entroques.
3- Indiquez au waypoint 3, quels monuments (1) sont visibles et de quelle(s) pierre(s) calcaire oolitihique ils sont composés : Vergenne, Micritique, Oolithique ou à entroques. Il est aussi apprecié d'avoir des photos des geocacheurs sur les lieux des EarthCache (bien sûr il est à éviter de photographier les monuments recherchés). Sentez vous inspiré de poster des photos de vous lors de cette visite ( optionnelle mais sympa)
In English:
In the geologic timescale, the Bajocian is an age or stage in the Middle Jurassic. It lasted from approximately 170.3 Ma to around 168.3 Ma (million years ago). The Bajocian age succeeds the Aalenian age and precedes the Bathonian age.
Oolite (egg stone) is a sedimentary rock formed from ooids, spherical grains composed of concentric layers. The name derives from the Ancient Greek word ᾠόν for egg. Strictly, oolites consist of ooids of diameter 0.25–2 mm; rocks composed of ooids larger than 2 mm are called pisolites. The term oolith can refer to oolite or individual ooids. Ooids are most commonly composed of calcium carbonate (calcite or aragonite), but can be composed of phosphate, clays, chert, dolomite or iron minerals, including hematite. Dolomitic and chert ooids are most likely the result of the replacement of the original texture in limestone. They are usually formed in warm, supersaturated, shallow, highly agitated marine water intertidal environments, though some are formed in inland lakes. The mechanism of formation starts with a small fragment of sediment acting as a 'seed', e.g. a piece of a shell. Strong intertidal currents wash the 'seeds' around on the seabed, where they accumulate layers of chemically precipitated calcite from the supersaturated water.
The city of Besançon has the immediate vicinity of Jurassic limestone (251 to 145mA) which provided rubble and cut stone for construction.
The limestone crinoidal: Limestone to articles crinoids (echinoderms) whose colors vary from pink to beige or gray. These limestones are lower Bajocian age (169-167 Ma).
The Oolitic limestone: The Great Oolite is a limestone composed of spherules two-tone color, beige and blue. This is the main stone in the loop. These limestones are age Bajocien upper (171-169 Ma).
Micritic limestones: limestones microcrystalline (or Micritic) and gravel (gravel quicontiennent) of white and beige hues. These limestones are Bathonian age (167-164 Ma).
The constructions of the oldest city (Roman relics particular) are built in Vergenne type of limestone that is an Oolitic limestone. This white limestone is soft enough to work more easily than the Great Oolite and more resistant to frost.
This limestone comes from quarries located either in Charcenne (Haute-Saône) or on the dominant heights Cléron (Doubs) or near Mandeure (North Doubs). The architects of that time did not hesitate to prefer quality stone at the expense of transportation, given the abundance of local limestone materials. (Quoting from Nicolas Carry)
Reminder: for earthcache, there is no cache to find, simply answer the following questions, so "log in the cache" Found it "and send me your answers proposals either via my profile or via the geocaching.com messaging (Message Center), and I will contact you in case of problems. "
1- Tell the waypoint 1, which monuments (1) are composed of limestone Oolitic type: Vergenne, micritic, Oolitic or crinoidal.
2 Specify the waypoint 2, which monuments (2) are composed of limestone Oolitic type: Vergenne, micritic, Oolitic or crinoidal.
3 Specify the waypoint 3, which monuments (1) are composed of limestone Oolitic type: Vergenne, micritic, Oolitic or crinoidal. We also enjoy seeing photographs of people visiting this EarthCache (but pictures relating to what you can see are forbidden). Please feel free to log photos of your visit...(this is entirely optional but funny)