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ced0015

Geology and Stratigraphy sources (books/websites)??

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ced0015

Hey all,

I've recently caught the "fossil bug", and I have been looking at geologic maps online to help determine potential hunting locations. Is anyone aware of an exhaustive website, book, etc. that labels stratigraphy? If not, what do y'all use to determine the age of certain locations/formations? Any advice is appreciated!

 

Thanks,

Caleb

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doushantuo

How about Fruitbat's Library,on this very same forum?

Meanwhile,when looking at maps,remember that igneous and metamorphic rocks do NOT good "source rocks" make

An example of concise(but not necessarily useful) geological information.

 

Harris et al 1998 Early Silurian Stratigraphic Sequences of Eastern Wisconsin.pdf

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opabinia

May Be Out of Date but try this site for fossil localities.

 

Topography can be found from a quick google search of "<insert your state here> topography."

 

Publication Database for Geology in the United States.

 

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doushantuo

An important part: the facies model:

 

 

silstjolSs.jpg

 

These facies/bathymetry(depth) maps give important information,because as you can see right away,certain organisms prefer certain habitats,MOSTLY,but not always,

depth-related.

These different depths can be recognized in the here and now by geochemical,paleontological(fossil content), sedimentological and stratigraphical means.

And yes, i know:beware of circular reasoning

Nota bene : most of these kinds of figures are vertically exaggerated!

The lithology changes the farther you get away from the paleo(Silurian)shore.Psammites/pelites/claystones/shale will generally be the rocks found the furthest from the paleoshore.Generally speaking,the distalmost grainsize is the smallest .This grainsize might also mean better-looking  fossils(more "pixels)".

 

Barring e.g. turbidite current/contourites/olistostromes etc. transporting the fossils,this will mean/tell you that in Wiscons the greatest chance of finding ostracods (crustacean microfossils)would be where the tidal flats USED to be in the Silurian.The tidal flat facies will be recognizable by eg. heterolithic stratification,current ripples,bidirectional current markings,the granulometry(grain size) I mentioned. 

Keep in minds that lithologies prograde,aggrade,disappear,or regress /backstep over time.

Also ,fossils and their surrounding lithologies undergo mineral changes(diagenesis,worst of all :metamorphosis) during their burial.

 

BTW,the USGS issues maps and reports,the older ones often being free downloads.

 

edit: I don't know what just happened here,please do not see this as a crash course in stratigrapy :P.

BTW,stratigraphy is NOT an easy discipline.Do not feel embarassed when you find the subject difficult.

Even stratigraphers themselves seem to keep forgetting Walther's Law

 

 

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doushantuo

the log:

logbeges.jpg

 

You can see straightaway that lithostratigraphy(rocks) and chronostratigraphy(time) are,generally speaking,two totally different things .

Notice the question marks on the left:that means not all of the chronostratigraphy is resolved yet!

The log is almost always a composite one!

 

 

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Fossildude19

The USGS website is helpful. 

Lots of information there.  

 

Once you find out the Formation names in your area, you can look for scientific PDF's that discuss the formations. (the website linked by Opabinia  -VERY OLD INFO- does tell you in many instance formation names and what county they are located in, as well as the age of the formation. 

 

Google the formation name, followed by PDF: For example: "Green River Formation PDF". 

Then you can look at the cited references, listed in the first paper, ... then search for those online. 
Lots of information out there if you know where to look. :) 

Regards,

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erose

Almost every state has a geological survey and along with the USGS that is one of the best sources of local stratigraphy and maps. 

 

Go here and look under publications: https://dnr.mo.gov/geology/

 

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