Ancient Tides and Length of Day: Correction

In our report “Late Proterozoic and Paleozoic tides, retreat of the moon, and rotation of the Earth” (5 July, p. 1001; correction, 6 Sept. , p. 13252), we examined sedimentary rock records that provided an indication of ancient tidal periods, when the moon was closer to the Earth and the length of a day was shorter. A comment by George E. Williams of the University of Adelaide, Australia, led us to reexamine our data from the Big Cottonwood Canyon formation (BCC) (13), which consist of three drill cores. We initially rejected core 2 because of its short length and chose core 3 because of what appeared to be less noise than core 1. Reexamination of the cores disclosed that the primary period of core 1 is larger than that for core 3, increasing the estimate of the sidereal period of the moon 900 million years ago by 2 days. Because both cores are samples from a common formation, this suggests that core 3 may be corrupted by loss of laminae. Substituting the core 1 data increased the estimate of the orbital period for the moon (relative to modern days) at BCC age. Core 1 parameter values were calculated (Table 14) ; this table also contains the correction of an error in the Elatina calculation of orbital parameters, which appeared in our report (13). View this table: Table 1. Corrected tidalite-derived lunar parameters using BCC core 1 data. Columns 4, 5, and 6 are based on column 3 (MLE). With the use of the whole span of time from BCC to Modern, the mean retreat rate of 3. 25 centimeters per year that we calculated earlier (13) is thus reduced to about 2. 1 centimeters per year with the use of Yoder's value for the present semimajor axis (2). But this new value rules out a constant retreat rate, because the Apollo value of 3. 82 centimeters per year requires a significant late increase. We thank Williams for his comment. 1. 1. ↵51. C. P. Sonett, 2. E. P. Kvale, 3. A. Zakharian, 4. M. A. Chan, 5. T. M. Demko, Science 273, 100 (1996) correction, ibid. , p. 1325. C. F. Yoder, in Global Earth Physics, T. Ahrens and J. Ahrens, Eds. (American Geophysical Union, Washington, DC, 1995), pp. 1-31. OpenUrl6Abstract/FREE Full Text7 1: /lookup/doi/10. 1126/science. 273. 5271. 100 2: /lookup/doi/10. 1126/science. 273. 5280. 1321f 3: #ref-1 4: #T1 5: #xref-ref-1-1 View reference 1. in text 6: openurl? query=rft. jtitle%253DScience%26rft. stitle%253DScience%26rft. aulast%253DSonett%26rft. auinit1%253DC. %2BP. %26rft. volume%253D273%26rft. issue%253D5271%26rft. spage%253D100%26rft. epage%253D104%26rft. atitle%253DLate%2BProterozoic%2Band%2BPaleozoic%2BTides%252C%2BRetreat%2Bof%2Bthe%2BMoon%252C%2Band%2BRotation%2Bof%2Bthe%2BEarth%26rftᵢd%253Dinfo%253Adoi%252F10. 1126%252Fscience. 273. 5271. 100%26rftᵢd%253Dinfo%253Apmid%252F8688061%26rft. genre%253Darticle%26rftᵥalfmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctxᵥer%253DZ39. 88-2004%26urlᵥer%253DZ39. 88-2004%26urlctxfmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx 7: /lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6Mzoic2NpIjtzOjU6InJlc2lkIjtzOjEyOiIyNzMvNTI3MS8xMDAiO3M6NDoiYXRvbSI7czoyNToiL3NjaS8yNzQvNTI5MC8xMDY1LjcuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9