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Comment by Warren on June 30, 2008 at 3:19

The Claiborne Group is a group of formations (rock units). Northwest Louisiana is structurally "high", that is, rock units that are buried deeply elsewhere have been raised up to the surface or near the surface. In northwest Louisiana, the Claiborne Group is not present because it has been eroded away. The older Wilcox Group is what is at the surface (or just under the layer of soil) in northwest Louisiana.

The chart gives the various formation names for Texas but lumps them all into the Claiborne Group in Louisiana. Actually, some of the same names are used for the age-equivalent rocks in Louisiana.

The Louisiana Geological Survey has a simplified geologic map available online:
http://www.lgs.lsu.edu/deploy/uploads/gengeomapla.pdf It may be of some interest to those on this discussion group.

Comment by Les Bamburg on June 28, 2008 at 4:28

Actually I realize the Nacatoch is less than 1000' deep and is productive in the Caddo Pine Island Field.

Comment by Les Bamburg on June 28, 2008 at 3:18

It would represent a geologic formation (rock layer). It would be very shallow and is either not present or not productive in NW Louisiana. For example the older and deeper Tokio Formation is only ~ 2000' deep in the Arkana Field and some of the shallowest production in the region. The equivalent of the Claiborne Group is very productive in SE Texas (Yegua & Cook Mtn Formations) and is about 8000' deep near Houston. Shale Geo could provide more accurate information.

Comment by Jaybird on June 28, 2008 at 1:30

Can anyone explain to me what the "Claiborne Group" pertains to on this chart?

Comment by Warren on June 27, 2008 at 2:46

This chart shows the names of the various formations (rock units), their geologic ages, and their relative positions to one another from East Texas to Florida. Keep in mind that this chart is diagrammatic: it will not tell you how deep a given unit is below the surface. That varies tremendously from place to place. It also will not tell you how thick a given unit is, or even its thickness relative to another unit. Except for the James Limestone and the Louann Salt, it does not tell you what kind of rock each unit is (sand, shale, limestone, etc.).

What is does show is the various names of units and their relationship (spatially) to one another. So. if you hear these different units being discussed, you can get an idea of where they are relative to other units (such as the Hanesville). Remember, also, that although this chart may look complex, it nevertheless is a simplification. The details (rock types, sub-units, and such) are much more complex and vary from one area to another. (The further away from one sie to another, the greater the likelyhood of change.)

Hope this helps.

Comment by Les Bamburg on June 26, 2008 at 4:10

This just shows the depth of formations in relation to each other. So looking under S Arkansas/N Louisiana you can see the Haynesville Formation (both shale and sandstone) are located below the Cotton Valley Formation and above the Smackover Formation. There are other information sources that would provide a more detailed breakdown of the formation groups. For example the Haynesville Sand, Haynesville Shale & Bossier Shale are all located within the Haynesville interval. Shale Geo would be able to provide a better explanation.

Comment by Keith Mauck (Site Publisher) on June 25, 2008 at 4:11

thanks for the post..can you expain to some of us amateurs what this is explaining?