A tidal bundle is a

sedimentary structure Sedimentary structures include all kinds of features in sediments and sedimentary rocks, formed at the time of deposition. Sediments and sedimentary rocks are characterized by bedding, which occurs when layers of sediment, with different particl ...

that forms in tidal areas as a result of spring and neap

tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables ...

Overview

A tidal bundle sequence can be seen as a variation in bed thickness with a periodicity of 14 days (diurnal) or 28 days (semidiurnal). During the neap tide, when the tidal current strength is weakest, smaller quantities of finer grains are deposited. As the tidal variation grows larger, towards the spring tide, larger quantities of coarser material will be deposited which results in an increasing bed thickness. Bed thickness will be greatest at the spring tide and then decreases as the tidal variation grows smaller, towards the neap tide again and the thinnest beds.

Significance

The presence of tidal bundles depends on the presence of spring and neap tides, which can only occur in three-body gravitational systems (the Earth, the Sun and the Moon). Therefore, the earliest time from which tidal bundles can be identified gives a conclusive lower bound on the age of the Moon.

References

{{Use dmy dates, date=March 2022 Sedimentary structures

Overview

Significance

See also

References