Period Stratification in the late Pre-Cambrian through Phanerozoic Eons has Galactic Origins. The chronology is recorded in the ICS Geologic Time Scale in a covariant 417M-year interval set of Periods. The nine Period Set has separate interleaved three Period set also with a 417M-year fundamental, at repeating interleave points. This analysis comprises the eleven Phanerozoic Periods, and includes a Pre Cambrian as well as post-Phanerozoic Periods. The eight Period Group aligns to Sol Galactic Arm (GA) passage. The interleaved triple set aligns to Sol Central Bar (CB) alignment. Milky Way Sol CB alignment and GA passage controls geologic period chronology; the geologic pattern is stable and repeats.
The ICS Phanerozoic Eon geologic periods consist of two processes. 1) Central Bar extension bisecting three Phanerozoic period groups, Paleogene-Oligocene [34M], Permian-Triassic [251M] and Ordovician-Silurian [446M]. 2) Remaining Arm interceptions cross the remaining eight Phanerozoic Period terminator’s with a repeating sequence of intervals. Arm interceptions have a near zero deviation ‘sixth arm’ 417M-year Geo-Galactic periodicity in the ICS Geologic Time Scale.
Four ‘sixth arm’ intervals are found the ICS/USGS Phanerozoic and Pre-Cambrian stratographic interval. Three Phanerozoic 417M-year intervals interleave in the Phanerozoic ICS ‘International Stratigraphic Chart’. A fourth 417M-year interval reaches the Vendian (Ediacaran:Varangian) 563M date published in the ICS papers.
Borgzoic is a projected (fictitious) period. Cenozoic is a compendium of Periods from Cretaceous to present. ICS 2004 shows two periods, ICS 2008 four periods. Paleogene-Neogene (2004) shows more constraint and allows the CB effect (Oligocene notch conundrum).
GA Period Date Interval 6th Interval
Orion Spur -1
Carboniferous* 73 417
Devonian 57 417
Ordivician-Silurian 72 417
Cambrian 75 417
Vendian 54 417
Cretaceous 7M-yr Discrepancy:
References  and  indicate multiple glaciating (cooling) events in the early Maastrichtian preceding the accepted 65M Cretaceous Yucatan bolide event. The Geo-Galactic interval indicates 71MA as the end Cretaceous causal date. It appears From general reports (NAT-GEO et al), geologists report dinosaur bones have not been found dating to 65M. Signor-Lipps effect does not apply . Opinion: This discrepancy exists because of the notoriety of the Chicxulub Meteorite, which is contrary to geologic Maastrichtian stage studies, and is competing with reptilian extinction causality science.
Carboniferous 13M-yr Discrepancy:
Carboniferous contested date persists in present web sights, one being the Canadian Museum. The USG has recently updated in compliance with ICS . This article statistically contends the 286M date is accurate based on repeating Arm intervals. Some what related, Pre-Cambrian Eon dates[C] are more unconstrained . The tilde Pre-Cambrian entries are within ranges supported by published datum. All contested dates are not fabricated, but previous published date changes; consequences of stratographic state-of-the-art as well as scientific democracy. The Carboniferous is 417M-yr paired to the Scutum-Centaurous, (Borgzoic). These Carboniferous dates harbor geologic uncertain dating, but which the JPL Galactic Map projects precision 417M-yr arm Sol interception angle(s), formula shown below.
The Italicized date is projected as the next Geologic Period[E] Sol is about to enter as we exit the ORION Arm. Statistically, in another 58M-year the Borgzoic Period (authors license) is projected to end in the Sagittarius Arm. Borgzoic represents integration of technology with the organic, ‘present day’ biotechnology.
Geologic Congruence to the Galactic Arm structure.
The end of the Cenozoic (Holocene Extinction) is coincident to our current egress of the Orion Arm. Intra-Arm travel time (Orion to Orion, Norma-Cygnus to Norma-Cygnus, Perseus to Perseus) having the same precision as the Geologic zero deviation 417M-year period pattern. The geologic angles project the Sol orbital arm to arm intercepts, given by a 417M-year cycle through the NASA Milky Way Galactic Arm map. For clarity, the Geologic derived milky way map is shown in figure 1. Figure 2 shows the NASA Geologic overlaid map.
Figure 2 http://i192.photobucket.com/albums/z...tic_Galaxy.jpg
Angular Interception Formula:
For European language/visual sense, right is forward time. The bar rotates to the right in the Georgelin map. The arms pass Sol outwardly. Orion is Spur-O, the next arm Sagittarius is 48 degrees into the future. The Equation repeats indefinitely end to end in positive time to the right, negative time to the left. Equation subscript-O marks the Orion Arm. Angle (degrees) between arms is used. Due to BAUT presentation limits, 64o = 64 degrees.
Equ 1: [Spur-O +48o Minor +64o Major] (68.2 degrees +6 degrees) [Spur +48 degrees Minor +64 degrees Major] (68.2 degrees -6 degrees)
Geologic Terminus Formula:
Geologic sense of time is M for Million Years Ago. Thus the equation is reversed in orientation and polarity to angular version. Left to right is positive M, back in time. Right to Left is negative, forward in time. The SpurO is end Cenozoic. The Cretaceous is 79-7 in the past; -1M + 79 –7 =71M (1). The Equation repeats indefinitely end to end in past time to the right, future time to the left. The subscriptO marks the present geologic period terminus. Time between arms is used.
Equ 2: [Major +74M Minor +55.5M Spur-O] (79-7) [Major +74M Minor +55.5M Spur] 79+7
Geo-Galactic Sets are associated through the 2+2+2 galactic class structure as:
(Spur, Minor, Major)=>(Proterozoic, Vendian, Cambrian); 79-7Myear, (Ordovician-Silurian, Devonian, Carboniferous); 79+7Myear,(Permian-Triassic, Jurassic, Cretaceous); 79-7Myear; (Paleogene-Neogene, next Borgzoic, unnamed). Equation 2 generates all (non-CB) Geologic Period terminuses to within +/- 2M-year. This is the first equation ever to order the Geologic Time Scale of the Phanerozoic Era, and it extends into the Pre-Cambrian as well.
1) The Milky Way Galaxy Central Bar is rotating 0.863 degrees per million-year faster than our Sol Galactic Orbit. The Oligocene temperature notch aligns to a Central Bar 26(3) degree in advance of Sol orbital position. The Central Bar has a 6-degree bend (23 and 29 degrees). The Kvet Planetary Equidistant Rupture (PER)  is generally aligned to the Galactic Central bar.
The Geo-Galactic Chronology pattern suports the Cretaceous Paleogene date occurring 6M-year earlier than the Chicxulub 65Mya KT bolloid: ref  and .
2) The ICS Geologic Time Scale major period date pattern is now formulated!
3) Using http://www.atlasoftheuniverse.com/milkyway.html consensus map as a reference structure: Period Arm pairing follows: end Paleogene-Silurian [Orion], Cretaceous-Cambrian [Perseus], Jurassic-Pre-Cambrian [Cygnus], Triassic Proterzoic [un-named Orion symmetric pair], and Carboniferous [Scutum-Centaurus]. Devonian [Sagittarius].
4) This Geo-Galactic Chronology does not predict a Cambrian Explosion .
I added the Cambrian Explosion to cap the extent of these assertions. I presently see no periodic galactic correlation with this event, although ‘something’  did occur.
Two major stratification processes structure geologic chronology, CB  and Galactic Arms. Stratification structure is a repetition of CB plus three GA egressions. The galactic repetition has an alternating interval ascertained from geologic chronological dating. The three exceptions, Paleogene-Neogene and Odovician-Silurian are themselves 417M apart. The remaining P-Tr has a diametric at 668M, the Harland 1982 Varangian 670M start date .
M: million years ago. M is in earth annum intervals (year), Ma refers to a time span scaled to million years. Ma is different that M (years ago).
Phanerozoic: Scientific: ‘make life appear’. Geologic: Present to 542M.
Chronology: Temporal sequence of events.
Geo-Galactic Chronology: Galactic temporal geologic stratification. Geo-Galactic Chronology stratifies the Phanerozoic Eon with Periods
Kvet, Complete Periodical Geological Timetable, GeoJournal 24.2 417-420, August 1991.
 ICS Phanerozoic Geologic Time Scale
 Thorn: Terminal Cretaceous climate change and biotic response in Antarctic; USGS OF-2007-1047 Extended Abstract 096.
 Barrera: Global environmental changes preceding the Cretaceous-Tertiary boundary: Early-late Maastrichtian transition. Department of Geological Sciences, Univ Michigan Ann Arbor 48109-1063.
 Evidence for a large-scale Reorganization of Early Cambrian Continental Masses by Inertial Interchange True Polar Wander. Joseph L. Kirschvink, et al. Science 277, 541 (1997); DOI 10.1126/science.277.5325.541.
 The Spiral Structure of Our Galaxy Determined from Hii Regions. Y.M.Georgelin and Y.P.Georgelin Observatoire de Marseille, Observations de Haute Province. Astron & Astrophysics. 49, 57-70(1976).
 'The Chronology of the Geologic Record' N.J.Snelling 1985 ISBN 0-632-01285-4
 Evolution on Planet Earth-The impact of the physical environment; Rothschild-Lister ISBN 0-12-598655-6; 2003.
PS: This has been edited 20April2010 in partial due to the following comments. Some of the above statements can be interpreted as opinion, especially in a paradigm context.