The Earth undergoes astronomically dependent climate oscillations which are reflected in the Earth's sedimentary formations. In addition to the effects of lunar cycles and solar cycles, there are variations in eccentricity, axial tilt, and precession of the Earth's orbit. Sedimentation cycles can therefore be used to re-construct astronomical timescales
More than a century ago, just
before the invention of radiometric dating,
G. K. Gilbert realized that astronomically forced cyclicity in marine sedimentary archives can be used to estimate the duration of parts of the geological record. His estimates suggested that our planet was much older than the 100 million years (or even 20 m.y., by some accounts) that had been calculated by a thermodynamic cooling model of the Earth.
Gilbert linked his sedimentary cycles to perturbations in the Earth's orbit and rotation axis that are caused by gravitational interactions of our planet with the Sun, the Moon, and the other planets. These interactions give rise to cyclic changes in the eccentricity of the Earth's orbit, with main periods of 100,000 and 413,000 years, and in the tilt (obliquity) and precession of the Earth's axis with main periods of 41,000, and 21,000 years, respectively.
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While Earth scientists can read these archives to reconstruct paleoclimate, astronomers have formulated astronomical solutions that include both the solar-planetary system and the Earth-Moon system. With these astronomical solutions they compute the past variations in precession, obliquity, and eccentricity. As a logical next step, sedimentary archives can be dated by matching patterns of paleoclimatic variability with patterns in the computed astronomical curves. This astronomical tuning of the sedimentary record results in timescales that are independent of radioisotopic dating and are tied to the recent times through a direct match with astronomical curves. A major breakthrough came only during the last decades, when studies directed at establishing such astronomical timescales yielded unprecedented accuracy and resolution for the last 15 million years.
Breakthrough Made in Dating of the Geological Record
A 3000 m long ice core, known as the GISP2, has been drilled through the Greenland ice sheet. Clear seasonal variations are recorded in the ice, and by counting these one can date the core. But it's not just a matter of counting visible layers, but of using special independent techniques that can reveal hidden climatic conditions at the time the ice was laid down:-
The seasonal variations are determined using a variety of independent techniques.
Variations in ice morphology
Since the sun shines only in the summer, different densities of snow form in summer and in winter. There are about 12,000 of these pairs (12,000 years) in the top portion of the core, though, through compression, these are not apparent at greater depths.
Electrical conductivity
During the summer months, more nitrate is formed in the atmosphere than during the winter, making summer bands on the ice slightly more electrically conductive.
Seasonal variations in dust
The Greenland wind is stronger in the winter and greater amount of dust are deposited along with the snow. The bands show seasonal variations back to about 127,600 years ago.
Volcanic ash
The wind spreads ash from volcanic over Greenland. The ages determined from the ice cores can be compared to the ages of known eruptions.
Oxygen isotopes
Owing to the isotope effect (the heavier isotopes of the same element are physically more 'sluggish'), when it comes to phase changes in water (ice, liquid, vapour) different temperatures affect isotopic composition. The extra mass of Oxygen-18 compared to Oxygen-16, though small, makes it a little bit slower to evaporate from the sea. Also when water vapour condenses, the molecules with the heavier isotopes tend to preferentially form ice crystals. Thus, colder winter air contains less heavy isotopes in its water vapour and this is reflected in annual bands in the ice. Due to diffusion in the ice this method is only good for dating the most recent 10,000 years.
Summary
Without using any radiometric date, the 120,000 annual layers of ice in the GISP2 ice core not only falsify the theory of a 6,000-10,000 year old Earth but also the idea there was ever a global flood, 4,000 years ago.
I invite Christians to read Paul Seely's paper
"The GISP2 Ice Core: Ultimate Proof that Noahs Flood Was Not Global".