Petroferric contact and layers in GA
In the Coastal Plain region of the southeastern US, a few spotty areas have soils that formed in iron-rich, loamy to clayey, marine sediments containing thin continuous iron cemented layers. These layers may qualify as petroferric contacts, but taxonomically, petroferric subgroups have not been recognized in the US. The Darley soil series is an example:
soilseries.sc.egov.usda.gov/OSD_Docs/D/DARLEY.html
These soils are common in the uplands of Africa, the central part of Indonesia, and many other areas.
According to USDA-Soil Taxonomy, a petroferric (Gr. petra, rock, and L. ferrum, iron; implying ironstone) contact is a boundary between soil and a continuous layer of indurated material in which iron is an important cement and organic matter is either absent or present only in traces. The indurated layer must be continuous within the limits of each pedon, but it may be fractured if the average lateral distance between fractures is 10 cm or more. The fact that this layer contains little or no organic matter distinguishes it from a placic horizon and an indurated spodic horizon (ortstein), both of which contain organic matter.
If formed by pedogenic processes in association with plinthite, these layers are commonly referred to as petroplinthite, whereas ironstone is more commonly associated with geologic processes.
According to the World Reference Base for Soil Resources (FAO and Food and Agricultural Organization of the United Nations 2006), a petroplinthic horizon (from the Greek words petros, meaning rock and plinthos, meaning brick) is a continuous, fractured or broken layer of indurated material in which Fe (and in some cases Mn) acts as cement and in which organic matter is either absent or only present in traces.
Using GPR to Characterize Plinthite and Ironstone Layers in Ultisols. Available from: www.researchgate.net/publication/282805887_Using_GPR_to_C... [accessed Dec 09 2020].
For more information about describing and sampling soils, visit:
www.nrcs.usda.gov/resources/guides-and-instructions/field...
or Chapter 3 of the Soil Survey manual:
www.nrcs.usda.gov/sites/default/files/2022-09/The-Soil-Su...
For additional information on "How to Use the Field Book for Describing and Sampling Soils" (video reference), visit:
www.youtube.com/watch?v=e_hQaXV7MpM
For additional information about soil classification using USDA-NRCS Soil Taxonomy, visit:
www.nrcs.usda.gov/resources/guides-and-instructions/keys-...
or;
www.nrcs.usda.gov/resources/guides-and-instructions/soil-...
Petroferric contact and layers in GA
In the Coastal Plain region of the southeastern US, a few spotty areas have soils that formed in iron-rich, loamy to clayey, marine sediments containing thin continuous iron cemented layers. These layers may qualify as petroferric contacts, but taxonomically, petroferric subgroups have not been recognized in the US. The Darley soil series is an example:
soilseries.sc.egov.usda.gov/OSD_Docs/D/DARLEY.html
These soils are common in the uplands of Africa, the central part of Indonesia, and many other areas.
According to USDA-Soil Taxonomy, a petroferric (Gr. petra, rock, and L. ferrum, iron; implying ironstone) contact is a boundary between soil and a continuous layer of indurated material in which iron is an important cement and organic matter is either absent or present only in traces. The indurated layer must be continuous within the limits of each pedon, but it may be fractured if the average lateral distance between fractures is 10 cm or more. The fact that this layer contains little or no organic matter distinguishes it from a placic horizon and an indurated spodic horizon (ortstein), both of which contain organic matter.
If formed by pedogenic processes in association with plinthite, these layers are commonly referred to as petroplinthite, whereas ironstone is more commonly associated with geologic processes.
According to the World Reference Base for Soil Resources (FAO and Food and Agricultural Organization of the United Nations 2006), a petroplinthic horizon (from the Greek words petros, meaning rock and plinthos, meaning brick) is a continuous, fractured or broken layer of indurated material in which Fe (and in some cases Mn) acts as cement and in which organic matter is either absent or only present in traces.
Using GPR to Characterize Plinthite and Ironstone Layers in Ultisols. Available from: www.researchgate.net/publication/282805887_Using_GPR_to_C... [accessed Dec 09 2020].
For more information about describing and sampling soils, visit:
www.nrcs.usda.gov/resources/guides-and-instructions/field...
or Chapter 3 of the Soil Survey manual:
www.nrcs.usda.gov/sites/default/files/2022-09/The-Soil-Su...
For additional information on "How to Use the Field Book for Describing and Sampling Soils" (video reference), visit:
www.youtube.com/watch?v=e_hQaXV7MpM
For additional information about soil classification using USDA-NRCS Soil Taxonomy, visit:
www.nrcs.usda.gov/resources/guides-and-instructions/keys-...
or;
www.nrcs.usda.gov/resources/guides-and-instructions/soil-...