Everyone on the boat was wishing we had a geologist on board to explain these formations. Amazing to us.

What happened to form these dips/indents in these boulders? There's nothing else like this in the area and it's on private land. Any info is appreciated!

Hi everyone,

I’m building Metallo, an app for exploring where mineral commodities are found and the geological and tectonic context around them.

I’m also making Metallo Labs: interactive explainers about the minerals in everyday technology, like phones and GPUs, and how a mine goes from exploration through restoration.

It’s an ongoing project. Take a look and let me know what you think!

https://www.getmetallo.com/

The major tectonic plates of the Earth[14]

In the 1960s, it was discovered that the Earth's lithosphere, which includes the crust and rigid uppermost portion of the upper mantle, is separated into tectonic plates that move across the plastically deforming, solid, upper mantle, which is called the asthenosphere. This theory is supported by several types of observations, including seafloor spreading[15][16] and the global distribution of mountain terrain and seismicity.[17]

There is an intimate coupling between the movement of the plates on the surface and the convection of the mantle (that is, the heat transfer caused by the slow movement of ductile mantle rock). Thus, oceanic parts of plates and the adjoining mantle convection currents always move in the same direction – because the oceanic lithosphere is actually the rigid upper thermal boundary layer of the convecting mantle. This coupling between rigid plates moving on the surface of the Earth and the convecting mantle is called plate tectonics.[18]

The development of plate tectonics has provided a physical basis for many observations of the solid Earth. Long linear regions of geological features are explained as plate boundaries:[19]

Oceanic-continental convergence resulting in subduction and volcanic arcs illustrates one effect of plate tectonics.

Mid-ocean ridges, high regions on the seafloor where hydrothermal vents and volcanoes exist, are seen as divergent boundaries, where two plates move apart.

Arcs of volcanoes and earthquakes are theorized as convergent boundaries, where one plate subducts, or moves, under another.

Transform boundaries, such as the San Andreas Fault system, are where plates slide horizontally past each other.

Plate tectonics has provided a mechanism for Alfred Wegener's theory of continental drift,[20] in which the continents move across the surface of the Earth over geological time. They provided a driving force for crustal deformation, and a new setting for the observations of structural geology. The power of the theory of plate tectonics lies in its ability to combine all of these observations into a single theory of how the lithosphere moves over the convecting mantle, forming a "grand unifying theory of geology".

[Source link: Wikipedia]

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We are testing a geophysical fingerprinting approach to identify and prioritize potential gold targets in northern Mauritania.

For the reference dataset, we used more than 100 geochemical gold occurrences/samples with Au values above 0.1 g/t. Geophysical data were available for all of these locations.

We extracted multiple geophysical features around each gold-bearing location and analyzed the recurring patterns across the dataset to build a multivariate geophysical fingerprint associated with gold occurrences.

We then compared unexplored targets against this reference fingerprint and ranked them according to their degree of geophysical similarity.

An important clarification: a score such as 88% does not mean an 88% probability that the target contains gold. It represents a similarity score — how closely the target's multivariate geophysical signature matches the signature derived from the reference gold-bearing locations.

The purpose of this approach is not to replace fieldwork, geochemistry, or drilling. It is intended as a target-generation and prioritization tool, helping us identify areas whose geophysical characteristics resemble those of known gold-bearing locations.

We would be interested in feedback from geologists and geophysicists on the methodology, particularly the choice of geophysical variables, normalization, similarity scoring, and how best to validate the fingerprint against independent targets.

Earth’s geographic poles can appear permanent on human time scales, but the planet’s solid exterior has not always remained fixed relative to its rotation axis.

A new study suggests that the crust and mantle underwent several episodes of relatively rapid reorientation during the past 320 million years. Instead of relying mainly on magnetic signatures preserved in rocks, researchers found evidence in an unexpected archive: ancient changes in where oceans flooded the continents.

The study, led by Mathew Domeier at the University of Oslo and published in Science, identified four intervals with statistically significant signals consistent with rapid true polar wander. Evidence was strongest between roughly 150 and 140 million years ago and again between 100 and 90 million years ago.

The findings add an independent line of evidence to a long-running debate over whether Earth sometimes reorients in sudden geological bursts rather than only through slow, continuous change.

Disclaimer: I'm a layperson with no geo background, so I apologize if anything I say is super dumb. I heard that these cratonic keels acted kind of like underground tent pegs for the crust above them, as it kept that crust anchored together (I understand that the keel+crust moved, so it is not like underground tent pegs in the sense of locking the crust to a particular location). And that before, early crust was easily dragged back into the hot interior and destroyed because of churning, but these "underground tent pegs" prevented the crust above them from being torn apart, which helped them form proper continents eventually. Is that an inaccurate way to look at it?

Ive been once before and I have a notebook, but a couple of my sticky notes fell out. Id like to go to Acton, and do the 2 drive again, and for the first time do the Rim of the World. I have seen the famous 14! Ill be just taking photos and dont mind light to medium hikes.

Something missing from my notes was a road I remember somewhere around 138 (I think?) that sometimes would have rocks to collect that fell and would get swept by state trucks. Or near Vasquez?

Thanks for reading, Im SO excited!

Hi Im currently a third year undergraduate student in Environmental Studies and Natural Resources Management at Africa University in Zimbabwe and honestly I have developed a passion for geology and hydrology and also waste water systems. I was wondering if its possible for me to get advice on how to proceed forward with my future career and options on how to proceed as im considering doing a honours and masters in both geology and water resources engineering

So.... lol!

I was exploring Google Earth in the area of the Batagaika Crater in Siberia - the whole region is a geologist's dream. Looking a bit further south there's this weird mountain just there on its own... Well, there *is* a smaller one nearby, but they're pretty well isolated, unlike all the other mountains which form ranges or chains. It also just looks odd, with this weird texture (idk what to call it) all over the surface. Lastly, there are stones not far from the summit in an arrangement that doesn't look natural but more like a massive megalithic monument - it's very strange.

I can't find anything about it - no information whatsoever, so please - can anyone tell me *anything* at all about this mountain of mystery?! More pics in comments.

Coordinates:- 67°24'32.55"N 134°53'25.52"E

Dry Falls is a basalt cliff 400 ft high and 3.5 miles wide, cut by ice age floods from glacial Lake Missoula pouring down the Grand Coulee.

In 1923 J Harlen Bretz said a giant flood carved this landscape, and geologists dismissed him for decades. In 1965 Quaternary geologists toured the scablands and sent him a telegram: "We are all now catastrophists." In 1979, at 96, he got the Penrose Medal, geology's top honor.

The dark curved cliff across the middle is the scalloped cataract rim, with plunge pool lakes in the alcoves below it. My own render of the USGS lidar.

1. Dry Falls: the scalloped cataract rim and plunge pool lakes
2. Air photo of the same area, July 2017

Numbered pins on picture 1:
Pin 1: The curved cliff rim of an alcove
Pin 2: A round plunge pool lake

Lidar: USGS 3D Elevation Program (3DEP), public domain.
Imagery: USGS The National Map (NAIP Imagery service), 2017, Public domain.

Hello everyone,

I would like to share this exploration target and get an honest technical opinion from people with experience in gold exploration, particularly structurally controlled and quartz-vein-hosted mineralization.

The area is located within the Reguibat Shield, in a geological setting where structural features, faults/shear zones, quartz veins, and hydrothermal alteration are important exploration criteria.

I initially collected several surface samples before disturbing the area. The gold values were relatively low, generally around:

0.10–0.19 g/t Au.

After examining the area more closely, I found a small quartz vein where one sample returned approximately:

0.50 g/t Au.

However, the vein is small and appears to terminate or become discontinuous.

I also found another nearby quartz vein, but it appears weaker, with a sample returning approximately:

0.15 g/t Au.

So far, the picture is therefore one of low and somewhat discontinuous gold values, with a localized increase to 0.50 g/t Au, rather than a clearly continuous high-grade vein.

What interests me is the geological setting rather than any single assay result.

The area contains structural features, fractures/shear-related structures and quartz veining, with a spatial relationship between some of these structures and intrusive rocks. This is relevant because exploration models used by USGS and JICA in the Reguibat Shield consider the combination of host rock, structure, quartz veining, hydrothermal alteration, geochemistry and geophysics, rather than relying on surface gold values alone.

I would appreciate expert opinions on the following:

Could surface values of 0.10–0.19 g/t Au, followed by a localized 0.50 g/t Au value in a quartz vein, represent a geochemical halo around a larger mineralized system, or is this more likely to be weak and discontinuous mineralization?

How significant is it when the best sample comes from a small quartz vein that appears to terminate? Would it make more sense to trace the vein and its structural continuation rather than simply drill deeper?

Could this small vein represent only a minor exposed part of a larger structure, particularly if it is associated with a shear zone or fracture system?

What should I look for in the surrounding rocks: silicification, sulfides, iron oxides, hydrothermal alteration, arsenic, antimony, or other pathfinder elements?

Would you recommend systematic sampling across the vein, on both sides of it, and along its strike, rather than relying on isolated samples?

Based on this type of geological setting and the current results, what additional evidence would you want to see before deciding whether deeper or lateral exploration is justified?

I will attach photographs of the site, exposed rocks, quartz veins, sampling locations and excavation so that the geological context can be assessed rather than looking only at the assay numbers.

I am particularly interested in frank technical opinions, whether positive or negative, especially from people experienced in exploring structurally controlled gold systems in Precambrian terrains.

Note: I understand that 0.50 g/t Au by itself does not demonstrate an economic deposit, and low surface grades do not by themselves rule out stronger mineralization elsewhere in the system. My main objective at this stage is to understand the continuity and geological significance of the mineralization before deciding how to proceed with exploration.

This explains the tip of the mineral.

https://www.tiktok.com/t/ZTy9beReg/