#californiageology

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After years of passing these rocks, my dad and I finally stopped to visit them. I've been reflecting on my Jewish and Middle Eastern heritage and I really could feel myself as a descendant from the North African Islamic desert tribes , and of the grandmother's from the Torah and feel Allah/Hashem's agelessness and strength, mercy and resilience from looking at these ancient rocks moulded by the San Andreas Fault. Here I can feel the ancestors of the California desert, the Mohajve people, and so many untold histories that linger here (I mean no offense by my use of Hashem and Allah. I use these names in my personal beliefs) #mormonrocks #route183 #sandstonerocks #desert #mojavedesert #nofilter #elcajonpass #soyjudiayque #soyjudia #handspunyarn #handspunshawl #truthisinmyeyes #praisebetoallah #desertbeauty #californiageology
Deformation of human structures on the Calaveras fault part 4. The road here was previously patched, but en echelon fractures are developing due to continual creeping movement. Across the street, the homeowner is reported to have turned his front door upside down, because the house is warped so bad that he couldn't close it. This will prove to be a temporary solution. The following pictures were taken in-line with the developing shear in the street on the north and south side of the road. These points and the previous ones I have in my feed are mapped out where I observed them in #googleearth The Calaveras fault is an active branch of the San Andreas fault, with 3 seismically distinct sections. The southern portion is undergoing "aseismic creep" or in other words it is moving very slowly, rather than large jogs during bigger earthquakes. The City is Hollister, CA. . #geology #geologist #faultline #dextral #geomorphology #structuralgeology #earthquake #calaverasfault #hollister #california #science #nature #gooutside #earth #geologyfieldtrip #tectonic #platetectonics #geotourism #californiageology #roadsidegeology #geologyporn
I had the privilege of a meetup with Dr John Wakabayashi, the guru godfather of the Franciscan Subduction Complex, the other morning!! I brought several tubs of my Franciscan rocks and he took the time to look with interest at all of them. It was awesome!! He recognized most of them, was intrigued by a few and great info just poured out of him. One of them even fell into his category of “bounty rocks” ..rocks he’s been searching for that entitle the finder to free 🍺 🍺 !! ... I managed to take a few pages of notes as I kept handing him rocks while trying to digest everything he was saying at ⚡️lightning⚡️speed and I got enough info to post a bunch more of my finds. I knew he worked in industry before becoming a professor and it shows in his writing by the excellent blending of academic knowledge with applicability to industry and hazard mitigation. It turns out he wrote dozens of papers (about his years of unpaid Franciscan research) in his garage in the evenings after work!! ... His PhD was on the Franciscan and he’s never stopped exploring it or the Sierra and is an avid hiker and fisherman. ...he’s fished in over 700 high mountain remote Sierra lakes! He’s got many more papers swirling around in his head and hopefully, for our benefit, he will find the time to get them written down somehow in the midst of a very busy schedule. I have great respect for him and am looking forward to future field trips with him. 🍻 cheers John!! 🍻 Last pics are of the rock in his hand and he agreed this one was mysterious, definitely subduction zone deformation and the white crystals(?) might be Lawsonite forming. ...more rocks coming!... 😎 ... #geologistonboard #californiageology #franciscansubductioncomplex #metamorphicrocks #blueschist #vanlife #platetectonics #geology #geologia #california #geologyrocks #lawsonite #beer #beerforrocks #norcal #🍺 #structuralgeology #franciscanassemblage #ringoffire #rockhound #earth #geologist #sportsmobile
Here’s a present day example similar to what California looked like ~100mya: ... 1-2 Mt Mayon 🌋 the most active stratovolcano in the Philippines erupting in 1984. It’s erupted 48x since 1616. ..ridiculously dangerous eruptions 😵 thanks to @g_e_o_l_o_g_y_life for the video n pic. Check out his feed for lots of geology pics!! ... 3 shows the 5 most active volcanoes ..these all have PDZs (permanent danger zones) 4 Mt Mayon is ringed with cities and 1000s of people have died thru the years. Now attempts are made at evacuations but many refuse to leave. 73,000 people evacuated for this eruption... 5 the tectonically active plate boundary zone has 6+ mobile elastic tectonic blocks that are sandwiched and getting squeezed between 2 active subduction zones that are subducting towards each other (2 white lines with teeth) ...crazy!! There has also been clockwise rotation up to 90 degrees ...that deserves another post It’s now in the late stage of a closing ocean basin after ~50 my of movement ... 6 quakes in red clearly define the active tectonic zone between the subduction zones (now marked in black) ... #geologistonboard #californiageology #philippines #mtmayon #volcanology #igneous #stratovolcano #ringoffire #platetectonics #geology #geologia #pyroclasticflow #phivolcs #geologichazard #volcaniceruption #travel #earth #video
Here’s a great example of flame and load structures in lacustrine (lake) silt beds interbedded with lighter-colored rhyolitic ash layers of the Wilson Creek Formation that surrounds Mono Lake near Lee Vining, California. I love the way the flames have been preserved as the deposits erode. . These are a type of soft sediment deformation and occur syn-depositionslly or shortly after deposition while the entire deposit is saturated with water. Differential densities of the rock layers and fluid pressures basically cause the flames to be injected upwards like small diapirs as the load structures cave downwards. . This all occurred during the Pleistocene due to water/magma interactions during eruptive pulses of the Mono Craters just to the south of ancient Lake Russell (now called Mono Lake) Pic 5 shows the Wilson Formation with Mono Lake in background. . Last pic is an aerial of the Mono Craters with the high Sierra in the background. The Panum Crater rhyolite tuff ring with central plug dome shows well in the foreground closest to Mono Lake. As magma flash-heated groundwater to steam, the tuff ring was created before any lava reached the surface.. 😎🌋 ...... #geologistonboard #californiageology #monolake #flamestructure #sedimentology #flamestructure #leevining #monocraters #inyomonovolcanicsystem #easternsierra #rhyolite #travel #californiaadventure #geology #geologia #earth #nature #fieldgeology #instacool #highway395 #basinandrange Thanks to @tectoniccity for the first 2 pics
#monolake is a salty and alkaline lake #ooliticlimestone is formed in this mono lake is also know as #tufatowers Monolake is located in #monocounty #california #unitedstates #geologystudent #geologyrocks #geologylife #californiageology @s_h_r_e_y_a_s___revanna_12
EDIT: THE LOCATION HAS CHANGED TO ROOM 1432!! While we're getting close to finals week and we're all working hard, it's important to take an occasional break from studying. NVC Geology Club is showing "Chasing Ice" on campus next week on Thursday! Free event for everyone in the spirit of the holidays approaching!! . . . #Geology #Californiageology #NapaValleyCollege #studentclubs #NVCgeologyclub #chasingice #climatechange #california #northerncaliforniageology #geologystudent #napavalley #napacalifornia #winteriscoming
Tafoni n tuff. ••••• Tafoni are small cave-like features with rounded entrances and smooth concave walls. ••••• Tuff is volcanic ash that had been ejected from a volcano, settled and compacted into solid rock. Despite its name it’s actually not that tough. ••••• #geology #geologyrocks #geologizing #hiking #optoutside #nature #naturephotography #california #californiageology #earth #roadtrip #camelbak #tuff #volcano #tafoni #getoutside #drone #karmadrone #karmagrip #gopro #earthpride ••••• 🎵 @ramesesb 🎵
Two of my favorite things: beach rides and geology in action!!! Erosion rates in Isla Vista CA are 6”-1’/year. These caissons were originally installed 20-30’ from the cliff. Rising sea level is likely to increase the rate of sea cliff retreat even more. #beachride #californiageology #seacliffretreat #coastalerosion #engineeringgeology #sealevelrise
#optoutside hike on the Pacific Crest Trail through Vasquez Rocks with my father. ————————— I’ve driven by this place so many times in the past — It was great to finally explore this beautiful and fun area! Thanks to the Sierra Club for organizing this outing! . . . #wanderlust #explore #adventure #travelphotography #visiting #beautifulplace #nature #getoutside #optoutside #climbing #climbingrocks #sheexplores #ilovemylife #outdoorwomen #california #vasquezrocks #californiageology #californiarocks
It's not snow, it's sand. On my hike up to the deck of the #SantaCruzSandhills at @HenryCowellRedwoods.SP I saw several young #PacificMadrone trees along the edge of the forest, the southern #SantaCruzMountains skyline, and a @CalFire crew from #BenLomond working the back end of a controlled burn near the summit. The higher you go on the trail, the more sand you encounter. Why? Because at one time this summit ridge was the seafloor, and the sand rose with the land as it faulted upward into the sky. #CaliforniaGeology #SantaCruzCounty #Felton #TreehuggersIntl #ThatsMyPark #CAStateParks @CalParks @SavetheRedwoods @SempervirensFund
My aerial shot of the San Andreas Fault and Pinnacles National Park made last month’s cover of Lithosphere! The cliffs of Pinnacles NP, (in the background) consist of 23.5 Ma felsic and intermediate volcanic rocks that correlate with the Neenach Volcanics on the other side of the fault and 315 km away (maps as pics 2,3)—that’s 315 km of right-lateral slip on the San Andreas since those rocks were erupted! #geology #geoscience #sanandreasfault #pinnaclesnationalpark #fault #earthquakefault #aerialgeology #californiageology #california #journalcover #earthscience #platetectonics #structuralgeology
BAM 💥 I attended a monthly meeting of the Bay Area Mineralogists which happened to be at Steve Smale’s house. He’s a well known UCBerkeley math professor (retired) and has a huge mineral collection. Only a few specimens were on display but they were nice. The gold piece was stupendous: California crystalline gold doesn’t get any better this! The collectors in this group are impressively serious about collecting minerals; some have >4000 different mineral species in their collections! 😵 ... One of my favorite old timers was there .. he’s 98.5 yrs old now, still kickin n collectin! Here’s to 💯 Jack! #geologistonboard #californiageology #minerals #mineralogy #geology #gold #goldfever #crystallinegold #crystal #earth #science #nature #amethyst #pegmatite #tourmaline #fluorite #travel #insta #geologia #geoscience #instacool #bam
Serpentinites + carbonates Olivine to the rescue! Here’s an unusual creek cobble I found amongst high-pressure metamorphics and metabasalt breccias in a Franciscan melange zone. I wasn’t sure of its origin until I visited the mountains of ophiolite surrounding the headwaters of the creek ~15 mi upstream with @geologyfromabove (my last 2 posts) and then I knew exactly where my cobble came from: Pic 2-4 What we found here was an entire stream-bed of peridotite gravels completely encased in a Ca Mg carbonate cement matrix! ...a bumpy 4x4 cobblestone carbonate-concrete highway! ...so the brecciated clasts in my rock are all partially serpentinized peridotites and the white cement is Ca Mg carbonate bioprecipitate derived from the interaction of peridotites with alkaline water and CO2 ...aided by microbes 🦠 Pic 5 And there were nice scattered carbonate deposits along the creek. Pic 6-7 Then we hiked up to the carbonate source, a cold alkaline springs seeping out of the ultramafic rock. There are several of these alkaline springs found in ophiolites along the Coast Ranges and they are the subject of research for NASA, JPL, Stanford and USGS because of their ability, with the aid of microbes, to pull CO2 out of the atmosphere and lock it up in the carbonates. ..which could be a way to permanently decrease atmospheric CO2 levels. ........olivine to the rescue! 🚨🚒🚨... ....Ophiolites are also considered analogs for Mars (which did not form a felsic granitic outer crustal layer like Earth did) so these microbes are of interest in origin of life studies. Cool stuff! 😎 #geologistonboard #californiageology #ophiolite #peridotite #platetectonics #structuralgeology #petrology #travel #norcal #nasa #jpl #olivine #geology #geologia #science #nature #alkaline
Here’s a nice green serpentine vein in partially-altered harzburgite peridotite I saw at the top of the ophiolite ridge we hiked up to in Sonoma County with @geologyfromabove ...this vein formed before the harzburgite was exposed at the surface... The rest of the pics are more downstream pebbles I polished to show off the peridotites at various stages of serpentinization. I especially like the green and orange one ...it may have originally been a dunite (90-100% olivine). There’s also a chart showing the compositional varieties of peridotites including harzburgite. So what’s the big deal about ophiolites?? Ophiolites are oceanic mafic (basalt) and ultramafic mantle (peridotites) rocks that have been shallow-thrusted up onto the edges of continents at convergent margins (like the subduction zone that existed along the coast of North America during much of the Mesozoic). Large blocks of oceanic basalt, oceanic sediments (chert) and poorly sorted continental sandstones (greywacke) are the most common ...but the more significant rock exposures are those that once straddled the “Moho” or Mohorovičić discontinuity which is Earth’s crust-mantle boundary. ...identified by an increase in the density of the rock. These higher density rocks are the peridotites and they give us valuable info about the interior of Earth. The serpentinization is due to hydration (aqueous alteration) at low temperatures similar to what happens to basalt as it converts to greenstone. This occurs at mid-ocean ridges, subduction zones and anywhere the rocks are exposed to water. Once they are accreted and sitting above sea level, the hydration slows way down and surficial weathering takes over which is why they’ve remained in the partially altered state.
Lakebed deposits exposed between sand dunes, Death Valley, California, USA. 1st pic shows setting- the lakebeds, which host creosote bush and the occasional Mesquite, support the dune field’s ecology. 2nd and 3rd images show closeups of the lakebed deposits, now broken by beautiful mud racks! It’s not entirely clear when these deposits formed, but they’re likely related to Glacial Lake Manly, which filled the valley to a depth of 200m - and so would have inundated this area- only about 10,000 years ago. #dunes #sanddunes #lakebed #drylakebed #sedimentology #stratigraphy #geology #earthscience #aeolian #eolian #windblownsand #deathvalley #desert #californiageology #mudcracks
Anyone else see the human profile? ••• Foreground: welded tuff/volcanic breccia. Background: lava flow capped ridge that was probably a valley when the lava originally flowed, protecting it from erosion while the rest of the landscape eroded down. ••• #geology #geologyrocks #geologizing #hiking #optoutside #nature #naturephotography #california #californiageology #earth #roadtrip #camelbak #mojave #mojavenationalpreserve #mojavetrail #holeinthewall #camping #weldedtuff
As we begin to approach the end of the Fall semester, we are planning one last meeting and a special field trip! Details will follow the meeting this Wednesday!! . #Geology #Californiageology #NapaValleyCollege #nvcgeologyclub #napavalley #northerncalifornia #fieldtrip #outdoors #westcoast #franciscancomplex #GeologyRocks
I got to visit another world yesterday!! 💫 Here are some videos at a ridgetop of weathering partially-serpentinized harzburgite peridotite (upper mantle rock) ophiolite exposure in Sonoma County that dramatically demonstrates how unsuitable mantle rock is for Earth’s surface and how barren their soils are. (..too low in necessary elements like Ca P K) The smoke from California’s largest fire on record added “ambience” to the otherworldliness of the stark spartan scenery. ...but as you can see there are some nice cypress trees and a few other plants that manage to thrive here. This rock is the same rock as my recent peridotite / serpentine pebble posts which came out of downstream creeks. @geologyfromabove set up the tour for this geological wonderland which is not open to the public. Check out his feed and >follow him< for more photos and for some great geology drone videos. I’ve got some more photos coming too 😎 ...and a huge shoutout to all the first responders out fighting these horrible fires 🔥 that literally sprang up overnight. #geologistonboard #firstresponders #paradisestrong #californiafires #californiageology #peridotite #serpentine #geology #geologia #platetectonics #ophiolite #petrology #structuralgeology #science #earthscience #fieldgeology #norcal
Here’s my 15 lb amphibolite beauty that I found in a Franciscan melange zone that’s especially rich in exotic blocks. Amphibolite is a common metamorphic rock at convergent margins like continental collisions and subduction zones. The reason for this is the abundance of its main protolith basalt which is the primary rock of all oceanic crust and thick basalts also sit under all continental crust. (dark brown in the bottom diagram pic 3) Amphibolite is not usually a foliated rock but in the first pic you can clearly see there is some foliation. ..more on this in my next post. So what is this rock doing in the Franciscan melange zones? Along with blueschists and eclogite, it tells us the pressure and temperature conditions and the most extreme extent of metamorphism that basalt experiences in the deeper parts of the subduction channel. Also, as well as being a high end member of the prograde metamorphism of basalt, it can also be a metamorphic protolith of retrograde metamorphism if it gets a chance to travel back up the subduction channel. ...in other words it can completely change back into blueschist and/or greenschist (and lower) facies rocks if it experiences lower temperatures and pressures. ..see pic 4 ... It can also be used to help determine which types of basalt (young or old mid-ocean ridge MORB, forearc or back volcanic island arc, seamount and also any rafting exotic blocks) have traveled down into the subduction trench. ..see top of pic 3 ... Indeed, thru the +100 million years of Mesozoic subduction of Farallon plate and East Pacific Rise oceanic crust all of these have made the journey down and back up and been accreted onto western North America. And since there is basalt-derived amphibolite under continental crust, these blocks can also get scraped off the upper hanging wall of the subduction channel and work their way to the surface just to keep it interesting!! ...FYI I read thru about 15+ papers before finally admitting there’s no way I can determine the protolith of my amphibolite without some serious geochemical testing ...argh 😫 😭 🤨 #geologistonboard #californiageology #franciscansubductioncomplex #amphibolite #platetectonics
Geothermic activity evident among these gurgling mud-volcanoes. The crust in this area South of the Salton Sea is spreading apart allowing heat from a shallow magma chamber to work its way up. No 4x4 required to see this. •••••••••••••••••••••••••• #geology #geologyrocks #geologizing #hiking #optoutside #nature #naturephotography #california #californiageology #earth #roadtrip #camelbak #saltonsea #mudpots #mudvolcano #drone #gopro #karmadrone #goprokarmagrip •••••••••••••••••••••••••• 🎵 @stickfiguremusic 🎵
I spy an ancient lava flow into the Mojave River canyon. The basaltic flow possibly dammed the Mojave River for a time, diverting the river to erode around it. 1. Overview of canyon walls with black basaltic lava flow. 2. Closeup of black basaltic flow with possibly part of the dam-plug at canyon floor. 3. Satellite view of area; the arrow is the perspective of first photo. #geology #geologyrocks #geologizing #hiking #optoutside #nature #naturephotography #california #californiageology #earth #roadtrip #camelbak #lava #lavaflow #basalt #mojave #mojaveroad #mojavenationalpreserve
Beautiful mafic dikes at this railroad cut. The mafic dikes are dark due to the higher levels of magnesium and iron within them. #geology #geologyrocks #geologizing #hiking #optoutside #nature #naturephotography #california #californiageology #earth #mojave #mojavetrail #mojavenationalpreserve #roadcut #railroadcut #igneous
A few more of my meta-basalts from the FSC Franciscan Subduction Complex. As you can see, the basalts are quite slivered up and nicely enmeshed in aragonite. Petrologically some still look red and relatively unaltered, others are altered or halfway altered to greenstone. Some of the aragonite looks macro-crystalline with green starry altered centers. 💫 Lots of alteration to greenish chlorite n epidote (n maybe something else) going on here. Last piece shows a softer aragonite vein sandwiched between two pieces of basalt. All rocks are wet. ... #geologistonboard #californiageology #franciscansubductioncomplex #franciscanassemblage #geology #geologia #science #coolrocks #geoporn #metamorphicrock #aragonite #basalt #platetectonics #earth #travel #insta #instacool #petrology #cobblestone #geologist #californiaadventure #norcal
I prefer to post rocks that I’ve actually identified ...but I’m posting this even though pretty much all I have is questions about this cool cobblestone I recently found in a central Franciscan belt melange zone... I know it’s subduction-related metamorphic and has fine-grained blue n green layers (assuming transitioning blueschist-greenschist facies) with a softer yellowish sheared? folded and micro-folded layer (assuming secondary chlorite pumpellyite clinozoisite phengite epidote??) that is chevron-folded with the blue layer (and in at least one spot faulted up against it ..shown in pics 2-3) ⚒ The blue layers have white crystals that may be secondary lawsonite? (formed due to serpentinization releasing fluids for metasomatic reactions) ...they seem to be forming by a chemical reaction at the boundary of the green n blue layers ...pic 5. Where there are no white crystals, the blue layers look grainy and under 10x the texture is knobby with very abundant round black? knobs that could be (altering?) garnets? ⚒ I don't know if the protolith (rock before metamorphism began) was downgoing basaltic crust or an upwardly exhuming higher-grade rock (amphibolite, eclogite, blueschist) that has retrograded to the finer grained material with the growth of secondary lawsonite. Note pics 2-4 were taken indoors, others outside in the sun ☀️ ...and the last pic shows the rock dry then wet. ⚒ Anyone seen anything like this??? ... #geologistonboard #californiageology #franciscansubductioncomplex #franciscanassemblage #blueschist #greenschist #highpressuremetamorphism #geology #geologia #science #geoscience #rocksarecool #cobblestone #earth #california #travel #nature #insta #geoporn #metamorphicrock #lawsonite #petrology #structuralgeology #nerdalert
Benitoite—The state gem of California, this is a barium titanium silicate mineral that displays magnificent color under fluorescence and makes a beautiful blue gemstone! It occurs in hydrothermally altered serpentinite; serpentinite is a green rock, so it’s very cool to see how this color of blue can come from a green rock! • • • • • • • • • • #minerals #mineral #mineralogy #crystals #crystal #crystalhealing #gem #gemstones #gemstone #rocks #rockcollection #geology #geologist #geologyrocks #likeforlikes #like4likes #followforfollowback #follow4followback #minerals_etc #spiritual #healing #meditation #california #blue #californiageology
Petrified 🌲🌲redwoods🌲🌲are found in many places in Europe, Asia and North America even Greenland! ...but California is the only place they’ve managed to thrive and survive to this day. Have you noticed that 🌲redwoods🌲 never grow crooked in a quest for more light like most trees? Nope, if there’s foliage blocking a redwoods upward path, it will sit patiently and wait for as long as it takes until there is an opening before growing taller. And as long as they get sufficient water they will live for thousands of years and die only under the most extreme of circumstances such as here in Sonoma County, California where many died during Pliocene volcanic activity of the Clear Lake Volcanic Field. They are truly majestic beings. Last pic is of the 🌋volcanic ash🌋 that buried the trees. This volcanic field is still considered active, is home to the world’s largest geothermal power plant and has produced mercury, sulphur, gold, Lake County diamonds and a beautiful red agatized mercury ore called myreckite that I’ve posted pics of previously. ... #geologistonboard #californiageology #sonomacounty #petrifiedredwood #fossil #california #franciscansubductioncomplex #geology #paleontology #earth #nature #science #redwoods #myfavoritetree #volcanic #volcanicash #igneous #travel #insta #instacool #earthscience #silica #treelover #lakecounty
Taking a short break from Franciscan melange rocks... I think I solved the mystery of my river polished “baggalutur” pebbles collected from Icelandic streambeds! ..stopped to see the wonderfully preserved petrified redwood trees (Sequoia langsdorfii an extinct species) by Calistoga and found what I’m assuming are lapilli, in this case hot round volcanic gaseous blobs, that exploded out of Mt St Helena ~3.4 million years ago and landed in volcanic ash of the same eruption. They look almost identical to the baggalutur pebbles!! Don’t you agree?!? And last pic is of the explanation provided on the tour guide which says they are iron concretions or obsidian 🤔...no no no I don’t think so! 🤷‍♀️ ... #geologistonboard #californiageology #icelandgeology #volcanic #lapilli #mtsthelena #calistoga #petrifiedtree #winecountry #norcal #volcanicash #geology #geologia #geoscience #science #geologyfieldtrip #california #rockcollection #travel #nature #earth #insta #historicallandmark #fossil #redwoods #pliocene #badpedicure #hiking
Obsidian Butte at the Southern shore of the Salton Sea. Evidence of the active spreading center here is everywhere. Highly recommend you go visit. No 4x4 required. #geology #geologizing #obsidianbutte #obsidian #salton #saltonsea #hiking #optoutside #imperialvalley #california #californiageology #roadtrip #nature #naturephotography #earth
Death Valley salt pan, California. The salt pan is the terminus of the Amargosa River, which starts near Ash Meadows, NV and flows southward down the Amargosa Valley, then turns north and empties into Death Valley (Slide 2). As Death Valley has no outlet, the water eventually evaporates and precipitates salt! Underlying wet mud gradually dries to form large polygonal shrinkage cracks, breaking the salt into polygons— and so upwards movement of water causes increased precipitation in the cracks. You can also see precipitation of salt as needles between the cracks (slide 3) from upwards movement and evaporation of water. What a place! #earthscience #geology #salt #saltprecipitates #saltpan #deathvalley #deathvalleygeology #precipitation #geoscientist #evaporation #sedimentology #californiageology #desert
Structures in Franciscan subduction melange zones ...from boudins, faults, folded faults and shear fabric in some of my cobbles to melange zones in mud matrix, melange fabric and asymmetric clast geometry along the California coast. (Pics 2-3 taken by John P Platt of USC) ... #geologistonboard #californiageology #highpressuremetamorphism #franciscansubductioncomplex #structuralgeology #platetectonics #cobblestone #blueschist #californiacoast #thrustnappe #geology #accretionarywedge #geologia #ringoffire #science #earthscience #
Deformation of human structures on the Calaveras fault part 3. 1) I'm cheating, can't believe I missed it. The path in front of the house pictured in #googleearth street view should be centered on the stairs, but the yard is shifting right where the path meets the steps. 2) in some areas the fault movement is distributed across a wider area, mostly because the fault bends and changes directions slightly. 3) en echelon cracks forming in the road since it was repaved, not sure when. En echelon cracks are usually present at the initial start of fault propagation, and consist of a series of parallel to sub parallel fractures that merge together with progressive shear. 4) offset sidewalk....this was stamped as being laid in 1910. So the offset should be the total movement since then right? WRONG. The slip is distributed over a wider area here on this street as in photo 2. 5 & 6) compare these two pictures. The second (6) was taken 6 months before mine (5). In that time frame, the walkway to the home has started buckling upwards. I spoke to the homeowner because she thought I was with the city inspectors, and was concerned about getting a fine (because kalifornia). After I assured her I was just a paisano from the old neighborhood and to fuhgettabahtit, she told me the house has been in her family for 100 years. If you place a ball on the floor on one side of the home, it rolls east, and on the other, west. 7) these points and the previous ones I have in my feed are mapped out where I observed them. Am I making you hot yet? Its okay you can tell me I'll keep it a secret (#geologyporn ) The Calaveras fault is an active branch of the San Andreas fault, with 3 seismically distinct sections. The southern portion is undergoing "aseismic creep" or in other words it is moving very slowly, rather than large jogs during bigger earthquakes. The City is Hollister, CA. . #geology #geologist #faultline #dextral #geomorphology #structuralgeology #earthquake #calaverasfault #hollister #california #science #nature #gooutside #earth #geologyfieldtrip #tectonic #platetectonics #geotourism #californiageology
Lake bed deposits exposed within the sand dunes at Mesquite Flat, Death Valley National Park, California. These dunes are the most accessible and most popular of the 5 dune fields in the national park. The lake beds speak to when the valley floor was inundated by glacial Lake Manly, near the end of the Pleistocene. #sand #sanddunes #wind #eolian #lakebeds #geology #geoscience #goldenlight #earthscience #earth_portraits #sediments #sedimentology #deathvalley #deathvalleygeology #deathvalleynationalpark #mesquiteflatsanddunes #ripples #windripples #california #californiadunes #californiageology
Got blue? 😲 Creeks are important outcrops when you’re mapping or rockhounding in Franciscan melange zones in the 🌲 redwood 🌲 forest! Most of the Franciscan rocks are large thrust nappes consisting of folded and deformed ocean sediments (mud), phyllite (moderate grade metamorphosed mud), chert and serpentine interlayered (sometimes chaotically) with continental greywacke (dirty sandstone ie poorly sorted sand with a high percentage of rock fragments) from submarine landslides ...but the real stars of this show are the “exotic blocks” which are broken blocks of (often unaltered) moderate to high-grade metamorphics formed deep in the crust. These blocks are always found in a matrix of the above rocks and come in a large range of sizes from hand samples to blocks as big as small islands. The blue rocks in this creek are part of a large block of blueschist facies metamorphics that are found in a melange zone. Melange zones can only be distinguished from each other when they have a different matrix that encloses the exotic blocks. ...ps I’m messing with ya on that last slide 😉 😎 #geologistonboard #californiageology #franciscansubductioncomplex #platetectonics #franciscanassemblage #blueschist #redwoods #geologyrocks #rockhound #fieldgeology #science #instacalifornia #nature #earth #hiking #photography #petrology #redwoods #🌲
I think I found the culprit for the trace fossils I found in the siltstone. You have no idea how satisfying this was to figure out! 😃🤓 #geology #geologyrocks #geologizing #tracefossil #siltstone #sedimentary #hiking #getoutside #beach #california #californiageology #earth #nature #naturephotography
Random sampling of pretty schists from my new collection of Franciscan Subduction Complex rocks 😎 1, 3 and 6 foliated blueschist with garnets and some high temp aragonite 2 micaceous blueschist with garnets 4 actinolite schist 5 hornblende schist ...this would have probably come off the bottom of the over-riding North America continental plate ...the metamorphic core or basement ig-met complex #geologistonboard #californiageology #franciscansubductioncomplex #platetectonics #geology #geologia #geologyrocks #blueschist #greenschist #mica #franciscanassemblage #cobblestone #highpressuremetamorphism #science #earth #geoscience #
Here’s a video of one of my FSC Franciscan Subduction Complex serpentine cobbles with what is possibly relict lamellar clinopyroxenes (cpx) in olivine bastites. The cpx would have exsolved or separated out of orthopyroxene while still at high temperature in the mantle peridotite. This would create a crystal with both pyroxenes present. Then as it starts it’s way up the subduction channel the rock begins to hydrate to serpentine but the lamellar structure survives. If the lamellae are found in olivine, it means the rock has dehydrated (after hydrating) and the serpentinized pyroxene converted to secondary olivine ...again with the lamellar structure surviving. Then it may rehydrate at lower temperature farther up the subduction channel and fully serpentinize ...or it may rise fast enough to get frozen in time before the conversion is complete as we see here! Thanks to @elkinm.hernandez who sent me a Japanese paper on this subject and another one I found from Norway that explain this process. #geologistonboard #californiageology #geoscience #franciscansubductionassemblage #platetectonics #geology #geologia #serpentine #olivine #pyroxene #peridotite #geologyrocks #metamorphicrock
Red hill, Route 395, Inyo County, California. About a mile north of fossil falls you come across a pretty small cinder cone called "red hill" (on the right of the photo) formed around a volcanic vent in the coso volcanic field, to the west of the great basin and range province. The cone is made up of unconsolidated pyroclastic material or "scoria", mainly basaltic in composition and quaternary in age, which was erupted as recently as 600 years ago during the Holocene. Activity in the region was as a result of mantle upwelling and consequent lithospheric extension and thinning, leading to subsidence. Geological activity started in the area around 17Ma during the Neogene period and continues today with thousands of tremors detected each year, meaning Red Hill may still have some life left in it. Rad. #geology #volcanology #science #california #sierranevada #volcano #USA #travel #californiageology #geologistsofinstagram #geoscience #geologist
Laws of inclusions and cross-cutting relations -in Cretaceous granodiorite of the Sierra Nevada. Hammer for scale. The dark (diorite) inclusions are the oldest, followed by the granodiorite, then cross-cut by the light-colored aplite dikes. 2nd photo shows a closeup of the aplite cutting an inclusion. Near Whitney Portal. #geology #earthscience #geoscience #igneous #igneousrock #geologictime #granodiorite #geologichistory #california #californiageology
What happens to mantle peridotite as it travels up the subduction channel?? Here are several altered peridotite cobbles frozen in time at various stages of alteration. I’ve recently collected these from a mélange zone of the Franciscan Subduction Complex. ✨✨As you can see they definitely don’t look like peridotite anymore ...neither do they look like serpentine!!✨✨ I don’t know the original composition (ratio of olivine to pyroxene) of the peridotite. Olivine alters more rapidly than the pyroxenes and I think my samples are rich in olivine with lesser or no pyroxene. ... 1 shows some cracked but still intact euhedral olivine crystals surrounded by a reddish brown matrix. This matrix is also olivine that is more altered. You can see some lines beginning to form in the matrix. This is called mesh structure. ... 2 is furthered altered and has lost all olivine crystal shapes to the naked eye. There is serpentine forming in the cracks. ... 3 micrograph showing mesh structure of an altering peridotite. Each of the cracked olivine crystals is still there but is surrounded by a thin layer of developing serpentine. The peridotite is hydrating as this is happening and greatly expanding in size. This hydration is fundamental to the serpentinization process. Note the more resistant pyroxene crystal in upper right. ... 4 is a close-up of well developed mesh structure with a thick dark serpentine (I assume) vein running thru it. ... 5 has a similar vein to 4 only here you can see bastites. I think these are altering olivine not pyroxene since it’s already serpentinized. ... more on this in next post. 6 is altered to the point of having a large nice bright green well-developed clump of serpentine surrounded by the altered peridotite. ✨✨✨pretty cool huh!?!?! 😎 #geologistonboard #peridotite #franciscansubductionmelange #franciscanassemblage #californiageology #platetectonics #serpentine #metamorphicrock #science #geoscience #cobblestone #creekwalk #rockcollection #instacool #
Cinder cone and Owens Valley, California. It's so great to be here-- and tomorrow I get to be back in Death Valley! The cinder cone is part of the Big Pine Volcanic field, a series of basalt flows and vents mostly between the towns of Big Pine and Independence. They cover some 500 km2 and erupted between 1.2 million to 17,000 years ago -- mostly along the frontal faults of the Sierra Nevada. That's important because it suggests the faults penetrate deeply into the crust. And that's granodiorite of the Sierra in the foreground. #owensvalley #cindercone #volcano #volcanic #lavafield #sierranevada #california #californiageology #geology #earthscience #geoscience
I love the San Onofre Breccia! Thought to be an ancient landslide, it contains so much variety. Jagged fragments of black schist, greenstone, white quartz, and the beautiful glaucophane schist displaying lavender and purplish tones, all spliced up by dikes of calcite while the tenacious Pacific sculpts interesting formations within it. #geology #geologizing #lagunabeach #breccia #sanonofrebreccia #beach #hiking #optoutside #pacific #california #californiageology #earth #nature #schist #naturephotography #erosion
I’ve got more cool Franciscan rocks coming but for some more background info of what’s going on, here’s a look at a computer modeled subduction trench showing the down-going ocean slab in green, accretionary wedge in orange at top, high pressure areas in bright pinks (not the grayish pink mantle at bottom) are in the swirled mixture of obducted rocks (those rocks returning to the surface) that are wedged between the down-going green slab and the continental slab above (light green and sitting on top of dark green basalt). These obducted rocks are the rocks I’ve been collecting and they consist of blocks of variously fresh, retrograded, altered and weathered high-pressure low-temperature rocks as well as less-metamorphosed oceanic crustal rocks (metabasalts) all swirled and mixed into matrix rocks the blocks are found in (serpentinite, phyllite, greywacke) ...and I’ve also found a few high grade metamorphics that were scraped off the bottom of the continental crust. These rocks form in a high-temperature high-pressure environment commonly found beneath continents. It’s a great combination of lithologies that can only be seen at the tops of subduction zones. There’s also a map showing major locations for this rock assemblage which include active subduction zones like the Ring of Fire and much older sutured areas where extinct subduction zones are found on continents (e.g. Brazil, Ural Mtns in Russia, the Himalaya arch) and the Caledonide Orogeny (an ancient suture now split apart by the opening of the Atlantic Ocean). Last map is a simplified map of California showing where the Franciscan rocks are located. #geologistonboard #californiageology #ophiolite #serpentine #basalt #blueschist #eclogite #platetectonics #geology #geologia #earth #map #franciscansubductioncomplex #rocksrock #geogyrocks #roadtrip
Sometimes we tend to see dikes as veins through the rock because we can’t see the third-dimension on a rock surface, but here’s a great example of a dike edge-on appearing more like a sheet. The latter is how we should remember to see them. This is a calcite dike through San Onofre Breccia. The sheets create perfect erosional fracture points and when fragments fall like this one, the dike sheet is nicely exposed. #geology #geologyrocks #lagunabeach #dike #geologizing #breccia #sanonofrebreccia #beach #erosion #nature #earth #california #californiageology #naturephotography #hiking #optoutside
Another wet FSC Franciscan Subduction Complex creek cobble ...I’ve got lots of them! This one appears to be blueschist fragments swirled thru ductile deformation at depth with something hard n white ..silica or massive grossular garnet or maybe a semi-jadeite??? 🤷‍♀️ ...and I think there’s also some retrograding peridotite clasts which are now fully altered to black serpentinite full of white veins. There is minor aragonite filling some fractures. . #geologistonboard #franciscansubductioncomplex #californiageology #platetectonics #petrology #blueschist #serpentinite #subductionzone #structuralgeology #geoscience #geology #geologia #creekwalking #wandering #geologyrocks #highpressuremetamorphism #franciscanassemblage
...another of my recent FSC Franciscan Subduction Complex cobble finds. This rock is so sparkly full of mica (probably phengite) which doesn’t show at all in the pics and it’s a dreamy ductile swirl of blues n greens with some red garnets. The surface protolith (rock before metamorphism) was most likely oceanic seamount or spreading-ridge basalt. It’s been prograde metamorphosed on its way down the subduction channel probably to high pressure eclogite facies then retrograded back down to blueschist w garnets and some yellow-green greenschist minerals like epidote n chlorite. Some high pressure higher temperature amphibolite could have also formed then retrograded back down to the deep true-green swirls of greenschist facies as well (actinolite). The retrograding occurred deep enough for the two rocks to co-mingle into these swirls. Then it was rapidly exhumed to the surface with no brittle deformation and entrained into a sedimentary mélange (olistostrome) where it sat until erosion thru the softer unmetamorphosed mélange exposed it ..then it rapidly tumbled down a steep creek into this beauty. That’s my best preliminary explanation for the story of this rock using only this hand sample ...to add details or other possibilities I would need to make thin sections and look under the optical microscope and run other diagnostic tests #geologistonboard #franciscansubductioncomplex #californiageology #franciscanassemblage #platetectonics #blueschist #greenschist #metamorphic #ductiledeformation #structuralgeology #petrology #creekwalking #hiking #geology #subductionzone #explore #instacool #geologia #geoscience #geologyrocks
Imprints in siltstone always grab my eye, but I’m not sure if my brain is turning these imprints into trace fossils or if they are, in fact, trace fossils. What do you think? Do you see hoof tracks? #geology #geologizing #siltstone #california #californiageology #sedimentary #tracefossils #optoutside #hiking #earth #nature #naturephotography
Can’t believe I’m a native second generation PG and never saw California’s Old Faithful before. Yeah it’s technically not a real geyser in that it was drilled years ago, but it’s been operating in its own for forever now. And yeah it’s $15 but even Yellowstone has an entrance fee. It’s awesome and it goes every 5-15 min!! Take that Wyoming and New Zealand!! It’s a must see!! Calistoga rules!!! #oldfaithfulgeyser #californiageyser #californiaoldfaithfulgeyser #californiageology #geologyrules #calistogageyser #californiaprofessionalgeologist
Metabasalt (metabasite) and aragonite cobble I recently found ...brecciated basalt in white aragonite (pressure conversion from carbonates) ...from a sedimentary mélange in the central belt of the Franciscan Subduction Complex. This formed (I think) in low temp and low-moderate pressure conditions in the shallow brittle zone of the subduction channel where rocks shatter (no ductile deformation). Then in the non-shattered basalt you can see parallel tension cracks! ...so although compression clearly dominates, this shows tension occurring also (probably in between waves/pulses of compression) #geologistonboard #californiageology #fieldgeology #structuralgeology #basalt #metabasalt #breccia #
Here’s the first of my wild cobbles (wet) from a mélange zone in the Central Franciscan Subduction Complex. This rock blows me away!! It’s mostly garnet-free blueschist (I think) with all kinds of alteration and ductile deformation and retrograde metamorphism going on. The matrix for the mélanges in this area is either a phyllite or greywacke (both of which are relatively undeformed!!) and nothing like the matrix here ...so I think this cobble is a representation of what is going on tectonically deep in the subduction channel 😲 and as these exotic high-pressure blocks of rock travel back up the channel to become entrained in the sediments of the accretionary wedge at the top of the subduction zone. What do y’all think?!?! 🤔...lots more of these coming! #geologistonboard #californiageology #franciscansubductioncomplex #franciscanassemblage #platetectonics #metamorphicrock #blueschist #greenschist #wild #wildrocks #structuralgeology #highpressuremetamorphism #earth #bluerocks
Lawsonite eclogite named after the Scottish geologist who named both the San Andreas Fault and the Franciscan Formation (now renamed). He also built the first earthquake proof in The SF Bay Area! I collected it in Tiburon, Marin County, California -I got 3 small HEAVY boulders from a fresh rip rap pile before it was all sadly buried during a construction project 💪🏼 ⚒ ...continuing the Franciscan Subduction Complex Chronicles: For about 70 million years (170-100 mya) basalt of the Pacific Ocean floor was traveling down several successive (now extinct and stacked up against one another) subduction zones along the west coast of North America, staying relatively cool and metamorphosing to blueschist as the pressure increased with depth. As the blueschist continued the travel and reached depths near the mantle where pressure and temperature are both high (but not quite high enough to melt the rock) it metamorphosed to eclogite -an ultra-high pressure UHP rock. The ratio and size of minerals here varies within the crude layering ..green omphacite pyroxene, red garnets, shiny flat white phengite mica, tiny blue lawsonite and a few other trace minerals. Most of the eclogite in a case like this continues to travel deeper into the mantle where it will melt and mix with mantle peridotites to create hot magma mixtures that will rise to form all combinations of plutonic (granitic +) and volcanic rocks. ...but small amounts of peridotite, eclogite and blueschist rise back up the subduction channel and get mixed in with surface sediments and end up accreted to continents where subduction is occurring. Erosion eventually exposes them and they provide proof of an existing or extinct subduction zone. The map shows where to look for these rocks 🗺 👀 ..................coming next are more of my recent finds showing how these rocks dramatically deform and alter as they rise to the surface .....get excited!! 😜 🤗😲 #geologistonboard #eclogite #californiageology #marincounty #metamorphicpetrology #petrology #mineralogy #platetectonics #geology #geologia #earth #science #franciscansubductioncomplex #mesozoic
Muchas gracias a estas geologas de SJSU, por crear este evento tan especial. ¤ ¤ A special shout out to these three wonderful SJSU geologists for leading this #amazing Geo-Hike. • • (Laura Mosqueda, Elizabeth Gutberlet, Ana Jaime). * * #henrycoe #henrywcoestatepark #goodvibes #geology #geologyinthefield #henrythegnome #findyourpark #encuentratuparque #geología #aprendemas #goodvibes #nature #naturaleza #geohikes #HuntingHollow #HH2018 #californiageology #geologists
So here’s the first of my Franciscan Subduction Complex blue schist posts. This is a basic high pressure but low temperature blueschist with normal foliation as seen by the aligned garnets. The blue minerals are small and don’t show the more visible schistosity of most other schists. When basalt starts it’s way down a subduction zone it shatters n brecciates (posts coming) where pressures are low. As it goes deeper and the pressure increases it goes thru complete metamorphism to beautiful blue glaucophane n lawsonite, sometimes with perfectly formed euhedral garnets like here and a few other minerals. It also undergoes ductile deformation ...posts coming about that. The green is probably greenschist facies minerals like actinolite, chlorite and epidote. Notice the green rims around the garnets! The white is high pressure aragonite. I’m not sure if they are prograde (original metamorphism as the basalt traveled down to increasing pressure) or retrograde (when pressure decreases as the rock travels back up to the surface) ..either way it’s a lovely rock. The facies diagram shows the pressures and temperatures of different metamorphic facies. Any rock type can theoretically find itself metamorphosed within these categories and the new rocks they become will all be different. For example, rocks other than basalt that undergo blueschist facies metamorphism become something other than blueschist. #geologistonboard #californiageology #franciscansubductioncomplex #california #rockhound #metamorphicpetrology #blueschist #highpressuremetamorphism #subductionzone #platetectonics #basalt #bluerocks #garnet #fieldgeology #rockcollection #travel #earth #mineralogy #instarocks #insta #
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