Questions tagged [geology]

The science comprising the study of the rocks Earth is composed of, and the processes by which they change. Some subfields of geology are petrology, mineralogy, and geophysics.

141 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
16 votes
0 answers
3k views

What is the global distribution of oil filled geodes?

In a general 40 mile radius of Keokuk, Iowa many sedimentary geodes can be found. They are abundant in the Warsaw Formation with the type section at Geode Glenn in Warsaw, Illinois. In one specific ...
user avatar
8 votes
1 answer
214 views

Can a braided stream create thick relatively continuous siltstone beds?

I am attempting to interpret an outcrop I went to. I suggested it was created by a braided stream. The one thing I cannot explain are prominent alternating siltstone and sandstone beds. There are ...
PattyWatty27's user avatar
7 votes
0 answers
190 views

How can we know the past height of mountains?

In Feynman Lectures on Physics Volume I, Feynman talks about the relation between Physics and Geology. He says “Mountains are no lower today, on the average, than they were in the past”. Through what ...
PineappleThursday's user avatar
7 votes
0 answers
110 views

Are there any known global effects of the Mediterranean sea evaporation and refilling?

This is a broad subject I realize, but I'm looking for specific geologically observed answers of global effects elsewhere, between about 5.96 and 5.33 million years ago when the Mediterranean sea was ...
userLTK's user avatar
  • 5,847
7 votes
0 answers
76 views

High-resolution laterolog array tool

Does anybody know if it is necessary to apply corrections to the reading given by this logging tool? Corrections such as bed thickness, borehole diameter, invasion, etc.? If so, is there anywhere I ...
Nicholas J.'s user avatar
7 votes
0 answers
129 views

Did an impact crater cause the formation of the gas fields in north eastern South Australia

In the paper High Impact Reservoirs, the authors claim that impact craters have lead to both the creation and destruction of petroleum source rocks, reservoirs and traps. Recently it was announced ...
Fred's user avatar
  • 24.7k
6 votes
0 answers
65 views

Formation of Hematite on Mars via Perchlorates as an Oxidizer

Hematite on Mars is generally thought to have formed either in pools of water or from volcanic activity. A comment to the answer to the question: How do hematite and magnetite form? states that ...
Fred's user avatar
  • 24.7k
6 votes
0 answers
108 views

Dating fluvial terraces with $^{10}\rm{Be}$

I've completed part A of the question below. Dating fluvial terraces with $^{10}\rm{Be}$ One way to determine the age of an alluvial deposit is to collect a series of samples from a range of depths, ...
Justin Grant's user avatar
5 votes
0 answers
51 views

What explains the angled stripes of mineral visible on the side of some islands?

I was exploring some islands by boat recently and I came upon some pretty impressive rock formation. I'm interested in finding what mechanism produces those angle mineral strips. Some of them were a ...
Nathaniel's user avatar
5 votes
0 answers
69 views

What is causing the crustal extension exhibited by the Basin and Range province in western North America?

Is there any link with the subduction of the Farallon Plate and the associated spreading center?
John McCarthy's user avatar
5 votes
0 answers
42 views

Can geochemical anomalies of stream sediment samples be used directly for mapping targets?

We know that geochemical dispersion in stream sediment is much widespread, facilitating discovering mineral targets in a regional scale. However, we also know that there should be discrepancy in space ...
tunar's user avatar
  • 331
5 votes
0 answers
52 views

Artifical Ore Genesis?

From my understanding, the formation of ores can be reduced to a simple three-step process of the removal of minerals from a source via some mechanism, the transportation of these minerals, and ...
zachery moïse's user avatar
5 votes
0 answers
225 views

How do the Andes get so high?

I'm interested in the limiting factors on the height of mountains. There is a very good explanation at https://www.quora.com/How-tall-can-a-mountain-become-on-Earth-Neil-deGrasse-Tyson-says-Mount-...
rwallace's user avatar
  • 715
5 votes
0 answers
66 views

Hypothetically, in the near future, could gas hydrate pingos erupt?

Could gas hydrate pingos erupt? If so, how quickly? And how much CH4 could they release? I'm sorry if the questions sounds silly. I'm new here and I don't know much about gas hydrates and oceanography....
Victor1995's user avatar
5 votes
0 answers
295 views

Why is Cambrian denoted with such a weird symbol?

I find Ꞓ such an odd-looking symbol. What's the historical significance, etc, of that symbol? Latin letter C with bar My understanding is, C was the Carboniferous, K for Cretaceous... why not ...
matt's user avatar
  • 151
5 votes
0 answers
81 views

How do you choose appropriate parameters for a lowpass filter when filtering a Bouguer anomaly?

I am trying to filter my Bouguer anomaly data to remove the short wavelength features. I have created a lowpass filter to achieve this, but I am wondering how I can more objectively choose my cutoff ...
Jet Yeti's user avatar
5 votes
0 answers
63 views

When will the weight of melted polar ice release the (currently stuck) subduction of the oceanic plate West of the Oregon coast?

Melted polar ice water makes the oceans deeper on average. The extra water on top of the oceanic plates makes them sink relative to the continental plates. This relative vertical displacement will ...
Forest's user avatar
  • 59
5 votes
0 answers
56 views

How do I generate a Moho depth model from seismic refraction data?

There are several permanent seismograph stations in Eastern Canada that have been recording arrival times for over 25 years. Using refracted Pn arrival times from natural earthquakes I would like to ...
Alex Koldewey's user avatar
5 votes
0 answers
54 views

How big does something have to be to cause an atmospheric event upon entry to the Earth's atmosphere?

The question is about a foreign object, ranging from an asteroid to a spaceship. How large does it have to be in order for its presence to start messing with the weather patterns, causing the like of ...
Hezine's user avatar
  • 51
5 votes
0 answers
73 views

How long do geysers typically stay active in Yellowstone?

Old faithful still erupts regularly, but at some point conditions in geology will change and it will cease activity. Wikipedia says that ~1300 geysers have erupted in Yellowstone, but only 1/3 of ...
f.thorpe's user avatar
  • 13.5k
5 votes
0 answers
103 views

What causes a change in composition from basanite to nephelinite?

Can the change in composition from basanite to nephelinite (i.e. increasing alkalis with decreasing SiO2) be explained in terms of fractional crystallisation, or only by a decreasing degree of partial ...
Leticia's user avatar
  • 51
5 votes
0 answers
131 views

Earth's inner core has an inner core inside itself. Are there three inner cores?

The Seeker.com article Earth's Inner Core Has Its Own Inner Core states that researchers at University of Illinois and Nanjing University in China have made a bizarre discovery. They've found that ...
Wiz Kid's user avatar
  • 51
5 votes
0 answers
812 views

I have found this structure in thin section. What is it?

I have been observing a nepheline specimen under polarized light and found some interesting places. I have taken several images. The first shows a micro-geode with parallel polarizers, second with ...
Petr Hykš's user avatar
5 votes
0 answers
1k views

Definitive values that classifies a rock as having “low”, “medium”, and “high” -strength, -hardness, -toughness, and -consolidation?

Question: Are there any widely accepted published values (or ranges) that classifies a rock as having “low” “medium” “high” -strength, -hardness, -toughness, and -consolidation (cementation or ...
Armadillo's user avatar
  • 591
5 votes
0 answers
56 views

Lithologic and hydrostratigraphic logs for the Deccan volcanic province, India

I need data on depth/thickness of of different lithologic units under Deccan Volcanic Province in MP, Maharashtra and Gujarat. For this if anyone can help in providing help in obtaining well log data ...
user42344's user avatar
5 votes
1 answer
156 views

Fossil ID: possible fauna fossil, from Perlis, Malaysia

I found this fossil while doing my fieldwork in limestone area. Description below may help to identify it. Location: NW Perlis, Malaysia (Setul Formation). Hilly Area. My Observation: Have a curly ...
mrm9719's user avatar
  • 51
4 votes
0 answers
33 views

Why are grain coatings an important mechanism for preserving porosity during burial in sandstone but not in carbonate?

I am writing a paper on the role of petroleum emplacement and grain coatings in preserving porosity during burial. I can find many sources discussing grain coatings stopping cementation in sandstone, ...
Coherence1537's user avatar
4 votes
0 answers
40 views

Which transparent mineral has the highest IOR? natural or lab made

I do apologize if this is the wrong place to ask this question. It's a rather simple question, but google gave me rather vague / random results, so I thought it might be better to ask somewhere like ...
Mister SirCode's user avatar
4 votes
0 answers
69 views

Regular-ish chipings in slate - weird weathering, hewn or a fossil?

When hiking in the Moselvalley (on the Calmont, to be precise) I found a slightly rhomboid piece of slate measuring about 10 by 11 cm, with a thickness of ca. 2 to 4 cm. As can be seen in the first ...
Erik's user avatar
  • 756
4 votes
0 answers
156 views

Patterns on Basalt

These Basalt rocks were hand cracked and used to build the walls on my home. Many of these rocks have these semi circular pattern, made of the basalt itself. It's just a bit darker than the rest of ...
Delson Roche's user avatar
4 votes
0 answers
94 views

How much would the ground be displaced in a magnitude 11 earthquake?

In a magnitude 5 earthquake, the ground shakes violently and it's often impossible to stay upright. This is caused by about 50-120 cm of displacement of the ground. But how much would the ground move ...
Wesley Adams's user avatar
4 votes
0 answers
67 views

How can we distinguish fold and cycle of sedimentation on a remote sensing image or in the field?

A fold is composed of stratigraphy that is symmetric and repeated. Cyclic sediments (also called rhythmic sediments) are sequences of sedimentary rocks that are characterised by repetitive patterns of ...
tunar's user avatar
  • 331
4 votes
0 answers
151 views

How would one go about drawing the contour lines for this map in order to draw the cross section?

Good Day. We Received this map as practice for our Geology university module and I have no idea how to draw the strike lines where the different heights intersect the different rock types in order to ...
KaapseDwergie2020's user avatar
4 votes
0 answers
39 views

Looking for videos/GIFs of petrification/permineralization

Do you know of any good animations, videos, or GIFs of petrification/permineralization? For some students verbal and written explanations don’t work, they don't always visualize well. So it’d be ...
IndependentThinker's user avatar
4 votes
0 answers
40 views

How do people determine initial ratio of the parent nuclide and daughter product in radiometric dating?

I understand that we have zircon crystals that prevent entering or leaving of nuclide or lead after forming. But how cand we understand what was the initial ratio?
Nikita Koritskiy's user avatar
4 votes
0 answers
207 views

how best to preserve the color of my amethyst geode?

Will bright indirect light cause an amethyst crystal to fade? How about an overhead LED light? How is best to preserve the color of my amethyst geode? Thank you!
G. Grant's user avatar
4 votes
0 answers
80 views

Is there a large undersea caldera in the Azores?

There looks like a large undersea circular feature (Google maps) about 120km across with its north edge on Sao Miguel Island and its south edge on Santa Maria Island. Has any work been done to say ...
tobuslieven's user avatar
4 votes
0 answers
131 views

Presence of cross stratified conglomerates in fan deltas

Why are cross stratified conglomerates found in deposits of fan deltas? I know that fan deltas are alluvial fans that deposit directly into the sea, hence they are poorly sorted.But could not ...
Faraz Gerrard Jamal's user avatar
4 votes
0 answers
84 views

What gravitational evidence do we have to counter the idea that oceans are formed when continents sink?

Is there some evidence for this based on gravity anomalies? I think I know how to tell if a mountain or structure is compensated based on bougeur and free air anomalies, but this really has me ...
spinelcity's user avatar
4 votes
0 answers
359 views

For slab rollback, what allows the subducting plate to begin descending at a steeper incline?

I recently learned about slab rollback, specifically of the Juan de Fuca plate subducting underneath the North American plate. From what I understand, the subducting plate over time begins descending ...
Kristina L's user avatar
4 votes
0 answers
30 views

Is the Ethiopian Plateau uplift still ongoing?

The rift zones around the Ethiopian Plateau, Mid Ethiopian Rift, are stil tectonically active since Somalia is separating from Nubia at a rate of 6–7 mm annually[1], and Arabia is rotating counter-...
Crustea's user avatar
  • 41
4 votes
0 answers
532 views

How to differentiate between normal and reverse fault, given a stress tensor?

I want to generate synthetic fault slip data using a known stress tensor. I am using a rotation matrix to get the orientation of the principal stress axes, and rotating the tensor [1 0 0, 0 phi 0, 0 ...
Prithvi Thakur's user avatar
4 votes
0 answers
70 views

How to integrate dry wells into groundwater level mapping automatically (inequality constraints on the interpolation)?

I'm interested in automating spatial interpolation of groundwater level measurements. I'm wondering if anyone knows a method for automatically taking into account things like dry wells, where I can't ...
bklag's user avatar
  • 41
3 votes
0 answers
70 views

How was the Boesmansgat Cave in South Africa formed?

I found nearly nothing about this sinkhole online. Apparently the cave has water dating back thousands of years. From where did this water come from. Is it just rain? And how dirty is the water now?
metaUser's user avatar
3 votes
0 answers
26 views

Google Earth type, online plate-techtonics demonstration over time

I once found an site on the internet that displayed the continents in a Google Earth type setting where you could spin, zoom and navigate around the Earth but in different geological time periods. You ...
karisiasafaris's user avatar
3 votes
0 answers
69 views

At what depth does the ground stop getting cooler/hotter(summer/winter) and it starts to warm up?Where is the MAT depth or geothermal crossover?

Lookin into geothermal cooling, and want to learn more about how temperature behaves at different depths, not too deep like 100 meters or so, ignoring unusual stuff like geysers and things. I want to ...
CMZneu's user avatar
  • 31
3 votes
0 answers
41 views

Coastal Hill Formation (Valparaíso, Chile)

This seems like a simple question, but I can't find much information on the web about this, and I haven't studied Geology or Geophysics. In Valparaíso there are a large number of "Cerros" (&...
bluejazzshark's user avatar
3 votes
0 answers
59 views

Why is the Colorado Plateau so stable?

The Colorado Plateau somehow has avoided all the tectonic activity around it over hundreds of millions of years. Is it just luck, or is there something about that chunk of crust? I have toured the ...
John McCarthy's user avatar
3 votes
0 answers
28 views

Water flows under the headwater and soil liquefaction has formed

A retaining wall 40 cm thick with variable height (thin-walled corner) is being built in the mountainous area. At the time of the geotechnical survey and design, there was no reservoir next to the ...
Risalat Bigachova's user avatar
3 votes
0 answers
192 views

How fast does sand degrade into silt, and silt into clay?

I am talking to some students about how soil changes, and I've heard from soil samplers that the texture of the soil, i.e. whether it is sand, silt or clay, doesn't change in a human lifetime. It ...
regular's user avatar
  • 31