Geology is the Way – The blog about all things geologic!

Questione di chimica: i cristalli di wollastonite di Norsi (Isola d'Elba)

Joshua Tree landscape

L'origine dei paesaggi granitici di Joshua Tree (California, USA)

mafic enclaves in monzogranite

Cosa sono le 'palle nere' nel granito di Sant'Andrea (Isola d'Elba)?

alkali feldspar phenocrysts in monzogranite

Cosa sono i 'sassi bianchi' incastonati nelle rocce di Sant'Andrea (Isola d'Elba)?

Rosso Ammonitico

Il calcare Rosso Ammonitico di Sassorosso (Garfagnana)

Nottingham Castle sandstones

Il fiume che una volta attraversava Nottingham – Le arenarie di Nottingham, Regno Unito

cross bedded sandstone

L'antico deserto dell'Isola d'Elba

Come la geologia di Walnut Canyon ha plasmato questi insediamenti pre-Colombiani

Camminando su un tappeto di cristalli di calcite GIGANTI (Moriglion di Penna, Lucca)

Neves granite with dyke

Quando due magmi diversi si incontrano (Neves, Alto Adige)

Le arenarie di mare profondo di Cala del Leone (Quercianella, Livorno)

Una passeggiata geologica attorno a Kyoto: la scalinata di Fushimi Inari-taisha

Manarola

Geologia di Manarola (Cinque Terre)

Nummulite

Geologia urbana: i nummuliti fossili delle mura di Girona

Cholla Cactus Garden

Il Cholla Cactus Garden (Joshua Tree) – un giardino in mezzo al deserto

contact granite gneiss

Abbiamo un contatto! Quando il magma incontra la roccia (Joshua Tree, California)

Castiglioncello beach

L'antico oceano nascosto sulla costa di Castiglioncello

La nascita di 'Geology is the way'

#rocktober is over! I hope your rocks are ready fo

#rocktober is over! I hope your rocks are ready for a spooky night!Some recommendations to survive the date: Don't pour water on olivine, or it will be like gremlins.Be careful of living fossils: they will come back as zombies.Your nextdoor petrologist is likely a vampire as in fright night.All work and no play makes Geology is the way a dull boy

Concerto of flutes! [➡️ Swipe and enjoy] The

Concerto of flutes![➡️ Swipe and enjoy]These are some of the most useful structures in the field! Flute casts are elongated scour marks carved by a current in soft-sediments, like mud, which are commonly preserved at the base of sandstone layers, as molds after sand filled them!They are useful in many ways. First, since they form at the base of strata, they tell you where the top and bottom of a layer are, which is a blessing if you have to deal with deformed sedimentary sequences with overturned or vertical strata (as in the image). Second, they are fantastic paleocurrent indicators: not only they are elongated parallel to the current but they form with a scoop-shaped end upslope/upstream of the sense of the current or, in other words, the 'flute' becomes thinner in the way of the current.Can you tell me towards what direction this current was flowing on some day several tens of millions of years ago?⛏Ligurian Flysch complexes (deep sea turbidites)🕑Cretaceous - Eocene🧭Antignano, Livorno, Italy#rocktober - day 30________________________________#flutecast #flutecasts #solemark #erosion #sediment #sedimentology #sedimentologia #stratigraphy #regionalgeology #fieldgeology #geology #geologia #geologyrocks #geologypage #geologyporn #geologystudent #geologylife #antignano #livorno #italy #fieldwork #mapping #stem #education #science #geologist

Tree bark? NOPE! Come look closer: these are rock

Tree bark? NOPE!Come look closer: these are rocks.When mudrocks are deformed at very low-grade metamorphic conditions, two main transformation happens: first, clay minerals are progressively turned into more 'shiny' micas, like illite. Second, these platy minerals get re-oriented by deformation in parallelism with each other forming planes along which the rock splits more easily, called 'cleavage planes'. Deformed mudrocks can experience a complex deformation history within an orogenic belt. It is actually common to find rocks that were squeezed in one direction and then deformed along another. As a result, more than one set of cleavage planes often form at angle with one another. Since cleavage planes are planes of weakness along which rocks split more easily, these rocks tend to break apart as these tiny, elongated slices, delimited by perpendicular sets of cleavage planes.This particular structure is called 'pencil cleavage'.Oh, no wonder in Italy we call these rocks 'Scaglia'. Scaglia means 'slice' and these rocks are so easily breaking apart that they are commonly associated with major landslides. The images from this post [➡️ swipe] are from an actual landslide that occurred near Lucca, Italy.⛏Scaglia Toscana Fm.🕑Upper Cretaceous - Oligocene🧭Val Fegana, Bagni di Lucca, Lucca, Italy#rocktober - day 29________________________________#scagliarossa #scagliatoscana #pencilcleavage #cleavage #foliation #schistosity #slate #landslide #tuscannappe #deformation #metamorphism #structuralgeology #tectonics #geologiastrutturale #tettonica #geology #geologia #geologypage #geologyrocks #geologyporn #geologyistheway #shale #geologyeverywhere #rockhound #geologyeverywhere #geologystudent #lucca #garfagnana

Why do you call them 'metalimestones'? Aren't they

Why do you call them 'metalimestones'? Aren't they marbles?A marble is a metamorphic rock derived from a limestone, so meta+limestone should be a synonym, right? Well, no. There is a subtle difference.The blue book of metamorphic rock (official IUGS nomenclature) recommends using the suffix 'meta' when primary (igneous or sedimentary) features are still recognizable in a metamorphic rock. In the case of carbonate rocks, if you can still see things like fossils or sedimentary structures, that's a metalimestone, not a marble. Marble should be used instead for a carbonate metamorphic rock consisting mostly of calcite where primary structures have been completely erased!For example, photo [1] shows folded... marble or metalimestones? These are metalimestones, because as you can see in [2] [➡️ Swipe ], we can still recognize wee fossils of Diplopora sp., a green algae that fossilized as these cheerios-looking structures. In [3], you can see another carbonate rock from a greenschist-facies complex that still preserves oncolites and other allochems... so that's still a metalimestone! On the other hand the rock in [4] flew to close to the sun (aka a hot igneous pluton that heated it up to 600 °C) and it is now completely recrystallized... a beautiful marble!I find this nomenclature useful because one can understand metamorphic grade already from the names given to rocks... i.e. I imagine the metamorphic grade to be much lower in successions of phyllite and metalimestone compared to successions of schist and marble.⛏[1-2] Metalimestone from Punta Bianca (La Spezia, Italy)[3] Metalimestone from Santa Maria del Giudice, Monti Pisani (Pisa, Italy)[4] Ortano marble, from the Ortano Valley (Island of Elba, Italy)#rocktober - day 28________________________________#limestone #limestonecoast #limestones #calcare #marble #marmo #metalimestone #metamorphicrock #fossil #fossils #sedimentaryrock #puntabianca #laspezia #elba #montipisani #italy #fieldwork #mapping #geology #geologie #geologia #geologyrocks #geologypage #geologyistheway #geologyporn #geologyscience #geoscience #geologyeverywhere

"Look to my coming on the first light of the fifth

"Look to my coming on the first light of the fifth day, at dawn look to the east"Well, I waited and waited but Gandalf never arrived. On the other hand, by looking to the east from the village of Marina di Campo (Elba) I spotted this huge chevron-like fold in the Cretaceous flysch: the prominent white layers are lime-turbidites, surrounded by black shales. I do not think there is any recent study on this fold and the moment I saw it it was love at first sight. I swear I will come back to map this beauty one day ❤️⛏Cretaceous Flysch | Flysch di Marina di Campo🕑Cretaceous🧭Marina di Campo, Island of Elba, Italy#rocktober - day 27________________________________#flysch #fold #folding #geology #chevronfolds #turbidite #sedimentaryrock #sedimentaryrocks #outcrop #structuralgeology #tectonics #geologiastrutturale #geologiaestructural #geologia #geologyrocks #geologyistheway #geologystudent #geologypage #geologyporn #geologyscience #geologyeverywhere #marinadicampo #elba #fieldwork #geo #rockhound

I can almost see them swimming. 🐙 Ammonites in

I can almost see them swimming. 🐙Ammonites in the red nodular limestones of the Rosso Ammonitico Formation of Sassorosso, Italy.Ammonites were formidable swimmers. They floated in the water column using a jet of water to propel themselves (like their living relative, the Nautilus). Their presence in carbonate rocks commonly indicates an open marine environment.Most of the ammonites shown here should be of the genus Arietites, but I am not a paleontologist myself: if you can provide a better ID, please tell me and I will update the description. P.S: there is also a gastropod among the fossils I have photographed in this formation.Sassorosso translates from the Italian as 'red stone'. It is a nice wee village built completely with blocks of Rosso Ammonitico limestone. Nomen omen - I guess.➡️ Swipe for more⛏Rosso Ammonitico🕑Sinemurian (Lower Jurassic)🧭Sassorosso, Villa Colemandina, Garfagnana, Lucca, Italy#rocktober - day 26________________________________#ammonite #ammonites #ammonitefossil #fossils #mollusca #arietites #fossili #fossilhunting #fossilhunter #rossoammonitico #ammoniticorosso #sassorosso #villacolemandina #garfagnana #lucca #calcare #limestone #lapidary #decorativestone #ornamentalstone #pietreornamentali #pietre #rockhound #geologyistheway #paleontology #paleontologia #geology #geologia

Metamorphism just gives that 'touch' that transfor

Metamorphism just gives that 'touch' that transforms sedimentary protoliths with little internal variability into beautiful metamorphic rocks... and this time it is not just my opinion, because you are looking at some of the finest commercial varieties of the Apuane marbles.There are endless varieties of marbles from the Apuane... 'ordinario' is the classic grey marble, 'statuario' is the marble used for sculptures like the David of Michelangelo and has a distinctive 'warm white' color... but my favorites are the marbles that derive from breccias, like this one, called 'marmo arabescato'.A breccia of limestone blocks in a clay-bearing matrix was indeed transformed by metamorphism into deformed marble blocks surrounded by a greenish chlorite-rich matrix. In the field, they are perhaps even better, when you can find these rocks around geological structures such as folds.⛏Apuane marbles/Carrara marbles (Marmi delle Alpi Apuane)🕑Hettangian (Lower Jurassic)🧭Cave delle Rocchette, Monte La Rocchetta, Massa, Alpi Apuane*coin diameter: 23.25 mm#rocktober - day 25________________________________#breccia #marble #marmo #carrara #carraramarble #marmodicarrara #marmoarabescato #decorativestone #lapidary #sculpture #sculptureart #metamorphism #deformation #geologia #geologiastrutturale #structuralgeology #tectonics #cava #quarry #geology #geologyistheway #geologyrocks #geologypage #geologyporn #massacarrara #alpiapuane #rockhound

For #rocktober 24 another super nice fold, again f

For #rocktober 24 another super nice fold, again from Punta Bianca.The whitish to brownish layers are metalimestones [metalimestone, not marble, 'cause fossils and laminations are still recognizable and are only partly recrystallized]. The black layers are phyllites. Everything is folded by this tight, recumbent folds [folds with horizontal axial plane].Some consider these folds to be refolded folds. Bonus geo-points if you can tell why from the image!⛏Punta Bianca sequence🕑Anisian-Ladinian (Middle Triassic)🧭Punta Bianca, La Spezia, Liguria, Italy________________________________#fold #folding #hammerforscale #structuralgeology #tectonics #geologiastrutturale #tettonica #geology #geologyrocks #geologylife #geologyistheway #geologypage #geologyporn #geologyeverywhere #geologystudent #rocks #rockhound #metamorphism #metamorphicrock #geo #outcrop #fieldwork #puntabianca #laspezia #liguria #italy

At this point, you know well that if I find a cool

At this point, you know well that if I find a cool rock I must stop and grab my camera!This is probably an aragonite vein [I say probably, because aragonite veins are commonly fibrous and brownish like this one in this area]. What is nice is that there are many 'steps'. The crystals are interrupted by several surfaces.We can interpret this structure as a crack-and-seal vein.A vein forms when the tectonic forces acting in rocks produce a tensile crack, i.e. a 'open void', which is immediately flooded by hypercritical fluids (i.e. water in pressure well beyond its boiling point) that deposit dissolved minerals as crystals, closing the void. In fibrous veins, like this one, crystals precipitate perpendicular to the vein walls. If this happens several time, which means that the same vein continues to get cracked open, we can witness multiple generations of crystals precipitated by fluids. In this sense, every 'surface' interrupting the crystals is a 'crack' episode, and every layer of fibrous crystals represent 'seal'-ing of the void.Another interesting structure of this vein is that it looks like it is folded at first glance, but crystals intersect with each other in these 'folds', so they possibly grew already starting from an wavy surface, but perhaps I am interpreting a nice boulder just a little bit too much.⛏Aragonite (likely) vein in marble, Marmi dei Monti Pisani Fm. (Calcari Ceroidi Auctt.)🕑Host marbles: Hettangian🧭Monte Castellare, San Giuliano Terme, Monti Pisani, Pisa, Italy*coin is 23.25 mm in diameter#rocktober - day 23________________________________#vein #geology #coinforscale #fibrous #fibers #calcite #aragonite #marble #aragonitecrystal #structuralgeology #tectonics #montipisani #pisa #sangiulianoterme #trekking #hiking #geologyistheway #geologystudent #geologist #geologists #gruppoitalianogeologiastrutturale #geologyporn #mineralporn #geologyrocks #rockhound #rockhounding #rockhounds

Lasagna rocks. Or maybe 'testaroli', since we are

Lasagna rocks.Or maybe 'testaroli', since we are in Liguria 🍝?In this place it is very common to find complex, disharmonic folds within sandstone layers. The chaos you can see in the sandstones contrasts quite sharply with the regularity of the strata above and below. It is like someone threw a lasagna in otherwise regularly bedded sedimentary sequences. You can see this very well in Fig. [4] and [6] of this series [➡️ Swipe]: the grey layers of mudstone above and below the sandstones are not affected by this deformation... and to say it all, only some sandstone layers show such an extreme folding.This is the result of soft-sediment deformation, when these were alternations of sand and clay. The water trapped in the sand couldn't escape because the clay layers act as impermeable barriers. As the heat and pressure increased, the trapped water caused liquefaction in the sand, and its original lamination was warped and distorted. Lithification finally turned sand into stone, preserving these delicate structures forever. Once again, as for yesterday's post, we were in the middle of a collision zone at the time (30 million years ago in the Northern Apennines), and who knows if earthquakes helped the process, maybe a little bit?⛏Macigno Sandstone🕑Upper Oligocene🧭Location is in Fig. [7-8]... It is one of the most photographed places on Earth, though I was the only was photographing the rocks 😓. It's Manarola (Cinque Terre, Liguria, Italy)*coin is about 23 mm diameter#rocktober - day 22________________________________#lasagna #lasagne #testaroli #manarola #cinqueterre #cinqueterreitaly #macigno #turbidite #turbidites #softsedimentdeformation #sedimentaryrock #stratigraphy #sediment #sedimentology #sand #clay #rockhound #outcrop #geology #geologia #geologyistheway #geologypage #geologylife #geologyrocks #geologyporn #fieldwork #naturephoto #rocks

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