Bob,
Thanks for your response and comments. Since retiring in June it is nice to be able to engage in a professional debate again.
When I first read/saw the master ""V"" horizon proposal my very first thought was ""surely eluviation is occurring, or has occurred at some time in the past"". All the E horizons with vesicular pores I observed in my career had eluviation occurring, or it had occurred in the past at some time. Even the vesicular horizons I observed in the Peruvian Desert had clay translocated during past El Nino events. The El Nino events pumped large amounts of water into the soil systems. Granted, the El Nino events may have been few and far between, but they were/are the driving mechanism behind many of the landforms and soils formed in the area.
In addition, in many of the very thin surface vesicular horizons, like those surface E horizons described in New Mexico natrargids, the loss of clay is more lateral than downward. The underlying Btn natric restricts downward water movement causing lateral surface movement of clay and other compounds. Whether the loss is downward, or lateral, it is still a ""loss"" and fits the definition of eluviation. I am convinced that eluviation has occurred in the proposed master ""V"" horizons.
So, for me, eluviation trumps the predominance of vesicular pores, and thus the master horizon designation should be an ""E"". However, if the quantity and size of vesicular pores is so predominant that infiltration and Ksat are significantly reduced, I would agree to the use of a horizon suffix to identify this property.
In your response you state, ""we are trying to get a picture of the whole elephant"" and ""our proposal presents ways to similarly identify the marginal vesicular horizons"". I agree we should get the whole picture. However, I suspect there has been far more detailed research into the vesicular horizons of desert soils than soils with ""marginal"" vesicular horizons that occur in cooler, wetter climates like those of the Colorado Plateau. Simply mining the data in NASIS, or the OSD database, is not the same as doing on-site comparative field studies between proposed ""V"" horizons and soils with ""marginal vesicular horizons"".
Concerning ways to designate ""marginal vesicular horizons"", how would the authors designate those thin surface horizons with platy structure, and a predominance of vesicular pores underlain by argillic horizons that were documented and described in the ustic, cool mesic soils associated with Pinyon forests at 16 inches of MAP on the Colorado Plateau?
The proposed definition of the master ""V"" horizon is so narrowly defined that any surface horizon with a predominance of vesicular pores would be designated a ""V"" horizon. The proposed definition is based mostly on the presence of a subordinate property (vesicular pores) that can legitimately occur in other surface A and E horizons.
Herein, lies my greatest objection to the master V. The authors agree that vesicular horizons have a ""range of expression"". However, at what point does the ""degree of expression"" of vesicular pores trump the genetic properties of an A or E horizon, and how does one define that breakover point?
A master horizon designation must be clearly defined such that it does not conflict with other master designations, and can be consistently identified in the field.
