23

Yes, there are lots of other factors. Factors affecting sea levels are no different from other natural processes: there is a large number of coupled, non-linear effects, operating on every time scale, and at every length scale, and across many orders of magnitude. The Wikipedia page Current sea level rise lists many of the known processes. And I wrote a ...


15

The idea of mass extinction is not that recent actually: Cuvier (1798), Buckland (1823) and d'Orbigny (1851) for instance were already talking about global catastrophes in earth history, linked to extinctions. But during the same period, Brocchi (1814) and Lyell (1832) proposed that extinctions of species occurred individually and were a gradual process (...


14

The width of a unit in a stratigraphic column, or 'log', sometimes represents the average grainsize of the rock. I can imagine it being keyed to some other property, but grainsize is common. You'll find lots of examples with a quick search for 'sedimentary log'. The height of a unit typically represents thickness if the vertical axis is length, height or ...


12

Sedimentation rate presently varies many orders of magnitude depending on the place you observe. The rate of sedimentation is also different. Some places have continual sedimentation, others have episodic sedimentation events. That is why charts that show changes in sedimentation rate are usually done for individual sedimentary basins, to determine the ...


10

Sandstone bodies in incised valleys can be good hydrocarbon reservoirs. Incised valleys form on the coastal plain and/or continental shelf during a fall in relative sea-level by a combination of fluvial and marine processes (e.g. fluvial erosion, headward erosion). Here's some coastal plain incision by the Orari River in New Zealand — look at those sand ...


10

I think this is very hard to answer this question as it is exactly this ambiguity that caused the International Commission on Stratigraphy to discard the names Tertiary and Quaternary for there are no clear limits to these era's. For example, the name Quaternary was only introduced some 70 years after the name Tertiary (source), and Neogene covered both the ...


9

The principle does not apply to all materials on earth as observed by us but is primarily concerned with sediments and rocks that form from sediments. Since sedimentation is a process driven by gravity grains settle one on top of others and there is no possibility to change that without adding additional processes. So from this perspective the principle is ...


8

The main interest of tephrochronology (i.e. dating sediments using volcanic ash layer) is specifically its instantaneity (relatively to geological timescale of course). It is precisely used for higher-resolution dating. An example would be the Kawakawa/Oruanui tephra from New Zealand which is a good isochronous marker bed at 26.5 ka, spread over 1500km, but ...


8

As Spießbürger also mentions in his answer sedimentation rates are local, and highly depend on sediment supply and accommodation room in the sedimentary basin. Global sedimentation rates are then just an average of all sedimentary basins, and are closely related to global erosion rates, although not necessarily the same depending on the time scales you look ...


8

There are definitely many examples of overlying Mesozoic strata that contain characteristic dinosaur fossils (and ichnofossils – i.e. trace fossils). One of the best examples is the Mesozoic stratigraphy of Utah and Colorado. However, most geologic intervals are characterised by less ‘famous’ fossil material (e.g. molluscs, trilobites or pollen grains). This ...


8

Your analogy with burying a box is not as accurate as you think. It needs specific sedimentary conditions for the remains of an organism to fossilize: being buried in soil is far from enough. Fossilization is such that, eventually, the fossil will be embedded in its stratum, meaning that tectonic events (as you suggest) that would displace the fossil will ...


8

No, Steno's principle of original horizontality (I'll call it the POOH) is not 'safe'. It is not a useful theory. Don't confuse it with the law of superposition (also due to Steno), which is useful. That law is, in a general sense, a foundation stone (ha!) of stratigraphy... with some caveats due to resedimentation and other processes. Why is the POOH ...


7

This link is a scientific talk by geoscientist Jerry Mitrovica (Harvard University) called 'Sea Level Fingerprints of Ice Sheet Collapse'. It's about an hour long, fairly technical, and focused on ice sheet contributions to sea level change (it was for an audience of other scientists), and has some good background related to this question. I highly recommend ...


6

As I see it there are no clear differences. There are, however, processes that are not compatible with a superposition principle. In geology, it is possible for layers to be folded and result in inverse age relationships. Packs of sediments can also be pushed over other layers during, for example mountain building, so that sequences are out of order or even ...


6

I will try to plainly answer your question about an artificial radionuclide production/diffusion resulting from human activities, without getting into the discussion of deciding if this is geochronologically relevant or not. I would point Figure 1 of this paper which indicate the average tritium (3H) levels in the northern hemisphere between 1945 and 2008. ...


6

Certain anthropogenic radionuclides have pragmatic advantages as markers for the start of the anthropocene. The advantage of radionuclides over anthropogenic stable nuclides is that the primordial production of all but a few radionuclides has decayed away. Thus natural background levels are below detection by sensitive analytical methods except in a few ...


6

If I remember correctly from my intro to paleo class, the terms articulate and inarticulate refer to a classification of brachiopods depending on the nature of their hinge. Articulate brachiopods have something like interlocking hinges (like a door hinge) made from serrated (or tooth like) parts of the shell. On the other hand, inarticulate brachiopods hold ...


6

Reading your comments I see that you're asking: so could we find for example 1km high limestone layers on earth ? The answer is definitely yes. Here's an example of a stratrigraphic geological section from Israel: source: Chronostratigraphic table and subsidence curves of southern Israel, Gvirtzman 2004, Israel Journal of Earth Sciences, 53 You can see ...


5

According "The youngest natural oil on earth" Doklady Chemistry vol. 438, pages 144-147: Prior to this paper, it was known that oil of the Guaymas basin is from young sediments and is 5000 years old. However, their work shows that oil in the Kamchatka volcanic area is "less than 50 years old". Oil is shown through carbon dating to have formed between 1962 ...


5

The chapter on the Anthropocene (Zalasiewicz et al., 2012) of "The Geological Timescale 2012" quote 3 papers that used artificial radionucleotides as stratigraphic markers: Schwikowski (2004), Turetsky et al. (2004) and Marshall et al. (2007). The first one (Schwikowski, 2004) used them in the context of dating ice cores from Alpine glaciers and the second ...


5

At least in Germany, another approach is very common („Verwitterungsprofil“): the width of layers shows their competence (resistance to weathering/erosion). So competent rocks (which don’t weather easily) “stand out” opposed to soft rocks. This is a very idealised representation of what a “real”, weatherd outcrop could look like. Edited to add: my ...


5

Big question. There is not enough data resolution at the moment, neither spatially nor temporally. There are geological periods thought to have undergone higher erosion rates based on the abundance of some sediment facies, such as during the Trias. There are also many sedimentary basins where where the evolution of sedimentation rates is well known. But ...


5

Fossils are only in very rare cases dated directly, because they do not contain sufficient radioactive isotopes for dating. Most geological periods are first and foremost defined by biostratigraphy- fossil assemblages, typically. The Cambrian period starts with the Fortunian stage - this stage is defined by the appearance of a certain trace fossil in ...


4

The best I have been able to turn up is the paid BD-logs service, which provides standardised lithology for borehole data. Open Geospatial Consortium data all appears to be listed on the Geoservices page, and does not appear to include a lithological database/lexicon. The French Geological Reference Platform does not appear to include a standalone database. ...


4

Here is another example where the law of superposition breaks. Mind you this is a natural process: meteorite impacts. A meteorite impact will excavate material from the bottom, and deposit it above the crater rims. Here's how: This will result in something that looks like this: Source for both images is http://www.lpi.usra.edu/exploration/education/...


4

As Peter correctly responds, for sedimentary rocks the principle of superposition is pretty much watertight except where tectonic superposition takes place. The latter can either repeat the sedimentary sequence, overturn it, or overthrust earlier sequences. There are many possible geometries, which creationists tend to misrepresent. The principle of ...


4

It does seem like it's impossible to know unless you have additional information. However, I think there is a hint in there. See this white halo around the intrusion? My guess (and I could be wrong here) is that it's not there for artistic reasons but rather it's there to provide a very strong hint. My feeling that this is some kind of metamorphosed contact ...


4

The standard stratigraphic nomenclature is a chronostratigraphic system based on palaeontological intervals of time defined by recognised fossil assemblages. That's wikipedia for you. This is incorrect. The point of a Global Boundary Stratotype Section and Point (GSSP) is to identify a global boundary with a very specific archetypical example. While a ...


3

OpendTect may do this, however getting to that stage would be a painful experience. Petrel can do this very easily, however, that is not anywhere near free... If you're a student, your department may have access to a few decent programs to achieve this. If you could find out what you have available, we might be of more help!


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