2007-03-12 14:16:56 · 5 answers · asked by bLeAcH-FAN 2 in Science & Mathematics ➔ Earth Sciences & Geology
There are volcanic deposits in Death Valley which can be radioactively dated (there's an impressive crater at the north end). A lot of the rest can be dated by the fossils.
2007-03-12 14:34:38 · answer #1 · answered by Engineer-Poet 7 · 0⤊ 0⤋
Dating of a geologic feature is usually determined by dating the rock layers.
The rules of geology state: that layers of rock on the bottom of strata are older than the overlying rock layers. The deposits on the bottom had to be in place prior to the rock layer above it.
Initially, they will try to identify the rock type (i.e. sandstone, slate, etc.) The composition of the rock will give some insight to the age of the layer. You may be able to use radioactive dating (i.e. carbon, uranium, etc.) This will give a large time period of when the layer was deposited.
To further refine the date of a layer geologists will look for fossils. Prehistoric animals such as crinoids, mollusks, trilobites, etc. will give more information on the age of the rock layer.
Ultimately, the exact age is never known. Why is this true? Because no human was present when the layer was actually deposited. We can only make educated guesses and attempt to use the evidence present to make those predictions.
2007-03-12 21:41:14 · answer #2 · answered by flyerave 3 · 0⤊ 0⤋
The age of the valley itself, as in: when it formed? Or the age of the rocks in Death Valley?
I'm going to assume that you mean the age of the rocks in Death Valley. Fossils, mostly.:
Here is a link to a table showing the relative ages of the older rocks in the Death Valley area (Precambrian to Permian). http://www.geosun.sjsu.edu/paula/rtp/dissertation/appendixa.pdf
And here's a link to general stratigraphy up to the Holocene (Recent).http://wrgis.wr.usgs.gov/parks/deva/devatime.html
As for the old stuff:
The Cambrian to Permian sedimentary strata have fossils that have been used to determine their geologic age. Fossil ranges have been tied, in the time scale, to absolute ages (as in millions of years ago) based on radiometric data.
Want a technical discussion of the dating of the Cambrian-Precambrian boundary in Death Valley? Go here: http://earth.usc.edu/research/sedlab/CorsettiHagadorn200.pdf
2007-03-12 23:40:42 · answer #3 · answered by luka d 5 · 0⤊ 0⤋
Same way they tell us the Number of Stars in the Sky or the distance to the Sun.
2007-03-12 21:19:53 · answer #4 · answered by cnsone 4 · 0⤊ 1⤋
carbon-14 dating
2007-03-12 21:24:22 · answer #5 · answered by Anonymous · 0⤊ 1⤋