Eriksson’s Dune, a remarkable geological formation in the Barberton Mountains of South Africa, provides a unique window into our planet’s ancient past. The tidal marks on this ancient dune, dating back 3.22 Ga, reveal the fascinating dynamics of the Earth-Moon system from the earliest chapters in "deep time.”

Earth-Moon System: A Dynamic Dance

Initial Conditions: Early Earth: Around 3.22 Ga, Earth spun rapidly, completing a day in about 13 hours.

Moon: The Moon orbited Earth in a low orbit, much closer than it does today.

Tidal Influence: As Earth rotated, its gravitational pull on the Moon created tides.

Friction: These tidal forces caused friction, gradually transferring angular momentum from Earth’s rotation to the Moon’s orbit.

Evolving Orbits: Over eons, the Moon’s orbit expanded, moving farther from Earth.

Earth’s Rotation: Simultaneously, Earth’s rotation slowed down due to tidal effects.

Layered Sandstone-Shale: The alternating layers of sandstone and shale reveal tidal cycles.

Analyzing the Tidal Record - Periodicity: Researchers found a periodicity of 15 layers in Eriksson’s Dune.

Neap-Spring-Neap Cycles: These layers correspond to variations in tidal strength during neap (weaker) and spring (stronger) tides.

Duration: Assuming mixed tidal systems, two cycles were either 30 lunar days (dominant semi-diurnal tides) or 30 sidereal days (dominant diurnal tides).

Earth-Moon Distance - Inference: Using Kepler’s third law and conservation of angular momentum, scientists estimated that the Earth-Moon distance 3.2 billion years ago was approximately 70% of today’s value.

Solar Day: Earth’s solar day was around 13 hours during this period.

Size of Specimen: 21mm X 19mm X 10mm; Weight: 4.6 grams; Ships with a Certificate of Authenticity, tag and information about the specimen. Macro pictures are 3X magnification and are of this exact specimen's rind and front. Faint layering can be seen in this 3.22 Ga specimen.

This material was legally and professionally collected. Now you have a limited opportunity to add this phenomenal geological specimen to your collection!

Ships with a Certificate of Authenticity, tag and information about the specimen.