Questions tagged [stratigraphy]

Stratigraphy is the study of rock strata and their intrepretation in term of absolute or relative age.

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What is deepest fossil we have found?

Deepest as in has had the most sediment above it. Obviously it has to be exposed to be found but it's still considered deep if its previously been covered by sediment. I should mention im not looking ...
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Database of geological group or formation exposures?

Is there any sort of database that provides the locations of exposures of certain geologic groups or formations? I ask because I have read that halite occurs in the Michigan Basin, and specifically ...
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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 ...
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83 views

Will a new glacial age take place on Earth or Holocene will become a new climatic epoch?

Pleistocene shows a switch between glacial and interglacial ages. Image source: global-climate-change.org.uk However, humanity is burning fossil fuels and increasing atmosphere's $\ce{CO2}$ content. ...
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Has a scientific consensus been reached concerning the formation of the Grand Canyon?

new student of Oceanography here! I'm studying Earth Science right now, and I found conflicting reporting re: the formation of the Grand Canyon; whether it was formed singularly by the Colorado ...
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Stratigraphy of limestone applied to the Great Pyramid of Giza

The Great Pyramid of Giza is made from blocks of limestone quarried from the Giza plateau. The pyramid is composed up of about 200 layers, with individual blocks varying in thickness from 20 to 60 ...
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76 views

What is the time period of these chalk/clay layers?

These limestone-clay rocks are very common in the Alps, they come from weather changes. How many years does it take to make one of the rock bands? 7 years, equivalent to an el-nino type event? 1000 ...
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109 views

Have we looked for human-like signals in the geological record?

This is somewhat of a follow up to some interesting discussion here about using synthetic radioisotopes to define the start of the anthropocene. It is also sort of related to a question asked here, ...
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How was the onset of the Cambrian period dated?

What dating method was used to determine the beginning of the Cambrian, and what was its margin of error? Was only one fossil dated, or were a number of similar fossils used?
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How are stratigraphic limits defined before the Phanerozoic?

International Commission on Stratigraphy defines the limits of geological ages and they create this chart: Click on image for full view. Acording to Wikipedia: The standard stratigraphic ...
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What are the key elements defining the separation between Jurassic and Cretaceous?

We have one mass extinction that seperates Trias from Jurassic, roughly huge volcanims over a long period of time, and Pangea starting to divide. Another mass extinction that marks the end of ...
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153 views

When sediments are deposited, do they sink into the earth?

I was listening to a geology podcast describing how sedimentary rock forms and later turns into metamorphic rock. As a river lays down sediment, the lower layers can eventually be several kilometers ...
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What are these basal rip up clasts in North Dakota?

Ther's an graph that appears that the KT asteroid turned the rocks into rubble 3000 km away, else there was a rain of big rocks from the sky. What are the rip up clasts and what is the way they were ...
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Difference between Proterozoic Nagari Quartzite and Gulcheru Quartzite

The Eparchean Unconformity forms the boundary between Proterozoic Nagari Quartzite and Archean Granite. Now, the Gulcheru Quartzite marks the onset of sedimentation , after Eparchean Unconformity in ...
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What did tunnel digging teach us about the formation of chains of mountains?

Since tunnelling is like making a giant horizontal core sample, what did the analysis of the extracted rocks teach us? Is the inside homogeneous or layered, are there "deformations", etc?
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Does seismic anisotropy follow stratigraphy?

This question is in the context of velocity model building for reflection seismic imaging (between 0km and 10km in a sedimentary basin). This is really a rock physics question disguised as an imaging ...
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162 views

Can we call the Precambrian eons (i.e. Archaic and Proterozoic) eras?

A diagram in a book I have places Archaic and Proterozoic under "eras". Is such naming correct? ICS says they are eons, so do most sources I could find, but a 1979 volume of "Treatise on ...
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781 views

Boundary problems in stratigraphy

What do geologists mean when they say - Cambrian/Precambrian Boundary problems or Cretaceous/Tertiary boundary problems?
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Are there secondary causes of sea level change?

Aside from the fraction of water stored as ice on land and temperature of the water, are there other factors that change sea level, and if so what are is the magnitudes of the these changes? For ...
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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 ...
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Methods and Software for Interpolating/Modelling of Stratigraphic Well Data in 2D/3D

I have some geologic well data. The lithologies have been interpreted, and stratigraphic columns have been drawn. The columns have been adjusted for elevation, and correlation has been done between ...
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Why is the concept of “mass extinction” a relatively recent development in geology?

The concept of "mass extinctions", with its catastrophic connotations, is a relatively recent development in the geological sciences. It evolved in the early 1980s, driven by two landmark publications ...
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429 views

Relative dating of intrusion

I am quite new to geology and have a realtive dating problem which I am a bit unsure of. I know very well the principle of superposition, principle of cross-cutting, etc., but am still a little bit ...
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158 views

There is soil in Archean? [closed]

Following a mobilista approach over geological time, and considering the Earth's internal heat as responsible for tectonic regime, which was involved in the "Permobile type" during the early times of ...
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What are 'articulate shells'?

I can not really find a definition, not even in a geologic dictionnary: What are articulate (resp. inarticulate) shells? To be more specific, the term is related to tsunami deposits (tsunamite).
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What makes pollen varieties useful index fossils?

What makes pollen varieties useful index fossils? Should pollen not be a poor index fossil?
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275 views

How have global sedimentation rates changed over the last billion years?

Do we have a graph of how sedimentation rates changed over time?
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186 views

Why pro-gradation occurs along coastal environments?

I am currently studying the deposition process in coastal environments and I came across a point which I do not understand concerning grading of grain size. According to "Petroleum Geology by North F....
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How accurate is the law of superposition?

Recently I started being more interested in the rational details of the sciences (... being often challenged about them by a creationist friend) and one of the creationist 'theories' I've encountered ...
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Which are the biggest methodological differences between the archaeological and geological approaches to stratigraphy?

Stratigraphy, or study of rock or soil layers (strata), was originally introduced as a branch of geology. However, it is often applied in other disciplines, especially in archaeology and paleonthology....
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where are the thickest limestone layers on earth ? (CaCO3)

What is the maximum thickness of limestone layers on earth? (Limestone or any other biochemical sedimentary rocks, for example chalk or coral reefs.)
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743 views

The youngest and oldest source rock for hydrocarbons in economic quantities

Most famous and productive source rocks for hydrocarbons are Paleozoic or Mesozoic, but there are also examples from the Neogene. Time is needed for the rock to reach the right depth and temperature ...
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Width of strata in stratigraphic column

I am trying to understand whether there is one "standard" meaning of the width of represented strata in stratigraphic columns, but I can find nothing online or in my geology books. I notice that, ...
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Incised valleys and hydrocarbon potential

The Wikipedia page on sequence stratigraphy states: Sandstone bodies associated with incised valleys are good hydrocarbon reservoirs. Can anyone elaborate on this statement and the reason behind ...
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286 views

Are there any geological periods found on top of each other that have dinosaurs of that period with in them?

In diagrams, It is common to depict geological periods to be directly on top of each other with fossils of that period within them. When looking for evidence of this, I have only found examples of ...
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Nuclear testing and the Anthropocene, a chemostratigraphic link?

The Anthropocene is described by Wikipedia as an informal geologic chronological term for the proposed epoch that began when human activities had a significant global impact on the Earth's ...
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661 views

Is the Principle of Fossil Succession accurate?

After wondering on the validity of the principle of Original Horizontality, I'm now focusing on the principle of fossil succession. This principle states that : Fossils of species that did not ...
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Is the Principle of Original Horizontality a good indicator?

Still reading a course on datation over multiple stratums that may have setting up the Earth's crust, I'm meeting for the first time the principle of original horizontality Steno. Is this theory safe?...
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Determining a rock age using volcanic ash layer

I wanted to know if volcanic ash deposits found in the geologic record are most useful in correlating the age of rock layers if the volcanic ash was distributed over a large area during a short period ...
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How to interpret the use of late and early Tertiary from older literature?

When reading older papers how should I interpret the use of "Late Tertiary" and "Early Tertiary"? Would these periods equate to Paleogene and Neogene, or was there a different accepted boundary age ...
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Is there a database of the geologic/stratigraphic units of France?

Is there a page where I can look up rock unit definitions for France similar to: https://www.bgs.ac.uk/lexicon/home.cfm http://www.bgr.de/app/litholex/index.php I did some searching for this, but ...