Newsgroups: sci.bio.paleontology, sci.geo.geology, sci.astro, sci.physics, sci.physics.relativity From: mathematician Date: Tue, 25 Aug 2009 03:05:26 -0700 (PDT) Local: Tues, Aug 25 2009 1:05 pm Subject: Re: About Tides at Moodies Group Time (about 3225 Ma ago) and some toy models Message-ID: References: <5584e757-1d90-4bff-8bcb-b54805b866c9@n11g2000yqb.googlegroups.com> ----text cut------ > Angular velocity of the Moon (n_m) would be 0.6507 (0.8296456598) > degrees per > hour (42.8 (43) mean solar days per synodic month which is about 40.8 > = 42.8-2 (41=43-2) mean solar days per sideric month at Moodies time > which is about 23.052 (18.0800078) mean > solar days per sideric month at present time. Earth-Moon distance is > then about r = (f*M*T^2 / (4*Pi^2))^(1/3) = 342218.904 (291047583.4) m ONE CORRECION 342218904 m SOMETHING NEW: Ericsson and Simpson mentioned value 18-20 sideral days at Moodies Group time (at 3.2 Ga) and Earth-Moon distance 45-48 Earth radii at 3.2 Ga. If day length at Moodies Group Time had been about 13.56 present hours (based on my article about linear extrapolations of Pannella's fossil time data) then Eriksson-Simpson estimated Earth-Mon distance would be much too small than they calculated above (45-48 Earth radii at 3.2 Ga). I conclude that there could be some misinterpretation in their article: Eriksson Kenneth A., Simpson Edward L. 2000. Quantifying the oldest tidal record: The 3.2 Ga Moodies Group, Barberton Greenstone Belt, South Africa. Geology, vol. 28, no. 9, September 2000, p.831-834, 5 figures. I think that their measurements, Fig 5A could be OK, but their interpretation 18-20 days at 3.2 Ga could be wrong. I suggest them to write again their article and try to find new and not contradictonary interpretation for this important ancient time data !!! Reference: Eriksson,K.A., Simpson, E.L., 2000. Archean Earth-Moon dynamics deduced from tidalites in the 3.2 Ga Moodies Group, Barberton Greenstone Belt, South Africa. Summit-2000-Reno, Nevada. 2000 GSA Annual Meeting--Reno, Nevada. Abs. No. 50602, Home Page. The American Geological Society of America. 1 page. -----Text cut--------------------- > (My last not confirmed and uncertain interpretation from figure 5A > (power spectrum of fig. 3A): > (9.833+13.11) / 2 = 11.47, two neap tides and two spring tides per > synodic month, > 23.6, two spring tides per synodic month, > roughly measured from the figure 40.5, this is minimum number of mean > solar days per synodic month. ONE CORRECTION: 40.5 could arise from spectrum aliasing effect so it could be wrong ? If the sampling time interval is one day (diurnal tides) then some frequencies below 0.5 *(1 / day) (Nyquist critical frequency) could be caused by aliasing effect (Nyquist criterion). If the sampling time interval is half day (semidiurnal tides) then some frequencies below 0.25*(1 / day) (Nyquist critical frequency) could be caused by aliasing effect (Nyquist criterion). How situation could be changed if tides are mixture of diurnal and semidiurnal tides ??? Reference: Mazumder Rajat, 2001. COMMENT Eriksson,K.A., Simpson,E.L., 2001. REPLY Quantifying the oldest tidal record: The 3.2 Ga Moodies Group, Barberton Greenstone Belt, South Africa: Comment and Reply. Geology, December 2001, pages 1159-1160. > So Mode = 11.47 – 23.6 – min(40.5)) > References: > 1. > Eriksson Kenneth A., Simpson Edward L. 2000. > Quantifying the oldest tidal record: The 3.2 Ga Moodies > Group, Barberton Greenstone Belt, South Africa. > Geology, vol. 28, no. 9, September 2000, p.831-834, 5 figures. -----Text cut-----------