lpetrich
Contributor
The Earth's rotation is very gradually slowing down, and the Moon is very gradually spiraling away.
Ancient shell shows days were half-hour shorter 70 million years ago
noting journal paper
Subdaily‐Scale Chemical Variability in a Torreites Sanchezi Rudist Shell: Implications for Rudist Paleobiology and the Cretaceous Day‐Night Cycle - Winter - 2020 - Paleoceanography and Paleoclimatology - Wiley Online Library
This work was done on a reef-forming rudist bivalve's shell. It involved taking tiny samples of it and then analyzing them. Composition and isotope-abundance variations could then be analyzed to find evidence of daily and yearly variation. The year was 372 days long back then, as opposed to 365.26 days today.
From Earth's rotation, our planet's rotation has slowed at 2.3 milliseconds per century over the last 2800 years, and that is the rate that one finds from that shell.
The authors of that work hope to examine older shells with their technique, to get a better picture of the Earth's rotation rate over geological time.
http://articles.adsabs.harvard.edu//full/1972Ap%26SS..16..212P/0000223.000.html
Title: Paleontological Evidence on the Earth's Rotational History Since Early Precambrian
Authors: Pannella, G.
Journal: Astrophysics and Space Science, Volume 16, Issue 2, pp.212-237
Bibliographic Code: 1972Ap&SS..16..212P
This paper a look back further. Some shells from 450 million years ago record day lengths of about 400 days/year. Here also, 2.3 msec/cy.
Ancient shell shows days were half-hour shorter 70 million years ago
noting journal paper
Subdaily‐Scale Chemical Variability in a Torreites Sanchezi Rudist Shell: Implications for Rudist Paleobiology and the Cretaceous Day‐Night Cycle - Winter - 2020 - Paleoceanography and Paleoclimatology - Wiley Online Library
This work was done on a reef-forming rudist bivalve's shell. It involved taking tiny samples of it and then analyzing them. Composition and isotope-abundance variations could then be analyzed to find evidence of daily and yearly variation. The year was 372 days long back then, as opposed to 365.26 days today.
From Earth's rotation, our planet's rotation has slowed at 2.3 milliseconds per century over the last 2800 years, and that is the rate that one finds from that shell.
The authors of that work hope to examine older shells with their technique, to get a better picture of the Earth's rotation rate over geological time.
http://articles.adsabs.harvard.edu//full/1972Ap%26SS..16..212P/0000223.000.html
Title: Paleontological Evidence on the Earth's Rotational History Since Early Precambrian
Authors: Pannella, G.
Journal: Astrophysics and Space Science, Volume 16, Issue 2, pp.212-237
Bibliographic Code: 1972Ap&SS..16..212P
This paper a look back further. Some shells from 450 million years ago record day lengths of about 400 days/year. Here also, 2.3 msec/cy.