2 ms·

How did the erosion affect the entire planet so thoroughly? Is it plausible we’ll someday find a place where the geological record of the missing years is still

by twhb 5y ago

How did the erosion affect the entire planet so thoroughly? Is it plausible we’ll someday find a place where the geological record of the missing years is still intact?

cbkeller 5y ago
Ah, so while there were ice sheets on every continent during these glaciations, there are actually quite a lot of places where sedimentary rocks survived the glaciations - perhaps as much as a fifth of the area of the continents (back-of-the-envelope, given that there is about a fifth as much preserved sedimentary rock per unit time prior to the end of the unconformity). Generally a lot of these regions where rocks from the "missing" interval are well-preserved are at the margins of the (paleo)continents. This is for two reasons, as far as we can tell: (1) erosion by continental icesheets is more hit-or-miss near the margins; "hit" if you're in an outlet ice stream, but "miss" if you're not, since marginal ice tends to be "cold-based" and generally not very erosive at the margins outside of the outlet ice streams; (2) the paleo-continental margins are where all the tectonic activity was at the time -- and while tectonic uplift won't help any, tectonic subsidence can help a lot if it makes a basin subside below sea level (which will protect against erosion).
- morphle 5y ago
  cbkeller, thank you so much for your answers! Its rare I read such good answers on the grand scale implications of someone's research. When you study plate tectonics, watch the Earth Story documentary [1], read Earth System History [2], Five Kingdoms by Margulis [3] or the books of Steven J. Gould [4] you get an overview of the history of planet Earth that geology, paleontology, biology and astronomy sciences pieced together in the last 150 years. But then you never hear about the new breakthrough research that happens after these publications. But now I have learned about a new mayor piece of the puzzle by these comments of cbkeller [5], thank you very much! If there is anything I could assist with, like writing complex (simulation) software in just a few thousand lines of code [6] for your research, you can reach me at morphle at ziggo dot nl. [1] https://en.wikipedia.org/wiki/Earth_Story https://en.wikipedia.org/wiki/Earth_Story and https://www.youtube.com/watch?v=UFcKEcyWhGQ https://www.youtube.com/watch?v=UFcKEcyWhGQ I'd be happy to point you to the other episodes [2] http://libgen.rs/book/index.php?md5=A3B163282F9B5A62A585C2305393B925 http://libgen.rs/book/index.php?md5=A3B163282F9B5A62A585C230... [3] http://libgen.rs/book/index.php?md5=DD4B4B5E17D924EC237155BD3120BFCD http://libgen.rs/book/index.php?md5=DD4B4B5E17D924EC237155BD... [4] http://libgen.rs/search.php?req=Stephen+Jay+Gould&column=author http://libgen.rs/search.php?req=Stephen+Jay+Gould&column=aut... [5] https://brenhinkeller.github.io https://brenhinkeller.github.io [6] Alan Kay lecture "Is it really complex or did we make it complicated?" https://vimeo.com/82301919 https://vimeo.com/82301919
  - cbkeller 5y ago
    That's great to hear, thank you!

by twhb 5y ago

How did the erosion affect the entire planet so thoroughly? Is it plausible we’ll someday find a place where the geological record of the missing years is still intact?

cbkeller 5y ago

Ah, so while there were ice sheets on every continent during these glaciations, there are actually quite a lot of places where sedimentary rocks survived the glaciations - perhaps as much as a fifth of the area of the continents (back-of-the-envelope, given that there is about a fifth as much preserved sedimentary rock per unit time prior to the end of the unconformity). Generally a lot of these regions where rocks from the "missing" interval are well-preserved are at the margins of the (paleo)continents. This is for two reasons, as far as we can tell: (1) erosion by continental icesheets is more hit-or-miss near the margins; "hit" if you're in an outlet ice stream, but "miss" if you're not, since marginal ice tends to be "cold-based" and generally not very erosive at the margins outside of the outlet ice streams; (2) the paleo-continental margins are where all the tectonic activity was at the time -- and while tectonic uplift won't help any, tectonic subsidence can help a lot if it makes a basin subside below sea level (which will protect against erosion).

morphle 5y ago
cbkeller, thank you so much for your answers! Its rare I read such good answers on the grand scale implications of someone's research. When you study plate tectonics, watch the Earth Story documentary [1], read Earth System History [2], Five Kingdoms by Margulis [3] or the books of Steven J. Gould [4] you get an overview of the history of planet Earth that geology, paleontology, biology and astronomy sciences pieced together in the last 150 years. But then you never hear about the new breakthrough research that happens after these publications. But now I have learned about a new mayor piece of the puzzle by these comments of cbkeller [5], thank you very much! If there is anything I could assist with, like writing complex (simulation) software in just a few thousand lines of code [6] for your research, you can reach me at morphle at ziggo dot nl. [1] https://en.wikipedia.org/wiki/Earth_Story https://en.wikipedia.org/wiki/Earth_Story and https://www.youtube.com/watch?v=UFcKEcyWhGQ https://www.youtube.com/watch?v=UFcKEcyWhGQ I'd be happy to point you to the other episodes [2] http://libgen.rs/book/index.php?md5=A3B163282F9B5A62A585C2305393B925 http://libgen.rs/book/index.php?md5=A3B163282F9B5A62A585C230... [3] http://libgen.rs/book/index.php?md5=DD4B4B5E17D924EC237155BD3120BFCD http://libgen.rs/book/index.php?md5=DD4B4B5E17D924EC237155BD... [4] http://libgen.rs/search.php?req=Stephen+Jay+Gould&column=author http://libgen.rs/search.php?req=Stephen+Jay+Gould&column=aut... [5] https://brenhinkeller.github.io https://brenhinkeller.github.io [6] Alan Kay lecture "Is it really complex or did we make it complicated?" https://vimeo.com/82301919 https://vimeo.com/82301919
- cbkeller 5y ago
  That's great to hear, thank you!