Modern dating techniques

A geologic map or report typically is only a summary of investigations that frequently involve the collecting and processing of hundreds of rock samples, followed by the evaluation and interpretation of data from a variety of analytical techniques.

A relative age is the age of a fossil organism, rock, or geologic feature or event defined relative to other organisms, rocks, or features or events rather than in terms of years.

The lower unit is formed predominantly by medium- to coarse-grained silty sands and is interpreted as a fluvial succession deposited before the Svratka River was dammed.

Biostratigraphy is the science of correlation of sedimentary units base on the identifiable fossils they contain.

Paleontologists examine fossils of all kinds, but micropaleontology (the study of microscopic organisms) is perhaps the most useful method of dating because the remains of tiny organisms tend to be better preserved, more widely distributed, and may provide more precise age determinations than larger shells or bone material.

The most important tools for paleontologists are collections of fossils and paleontological reports (with fossil plates for identification) from other locations in the region or around the world.

Micropaleontologists and palynologists work with microscopes or scanning electron microscopes (SEM).

Selected examples of correlation geochronology methods used by USGS scientists include: Paleomagnetic Dating - Under certain conditions, a record of the orientation of the Earth's magnetic field is preserved in rocks and sediments.

Paleomagnetic dating is based on correlation of measurements derived from oriented samples to established records of variations of the Earth's magnetic field through time.

Paleontology is limited to the study of sedimentary deposits where fossils are preserved, but can be used in establish relative ages of nearby igneous intrusion, faults, and other geologic features.

With the cumulative experience of centuries of paleontological research, the chronology of many fossil species are well established in context of both geologic time and distribution.

We thank Povodí Moravy, State enterprise, for reservoir level fluctuation and discharge data.

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