Page 36 - The Black Range Naturalist Vol. 4, No. 3

The Source of the material on this page.
The need for people to remain socially distanced has created a recent upsurge in live interactive presentations, using tools like Zoom and Webex. This trend has created a level of accessibility which has not existed before.
On April 9, 2021, for instance, we were able to “attend” a presentation by George Veni. Veni is the Executive Director of the National Cave and Karst Research Institute. Information about karsts on this page is taken from his presentation. Any errors are solely the responsibility of the editor.
His presentation was part of the Southern Wetlands Roundtable presented under the auspices of the New Mexico Department of Environment. Maryann McGraw and team have been putting these presentations on for years, one in the spring and one in the fall. Each season there are two roundtables, one in Santa Fe and one in Las Cruces. (Contact her directly to receive advance agendas and access information for the presentations.) We have attended live sessions in Las Cruces prior to this, but missed many because of the three additional hours of travel time that would require. We wish to express our appreciation of the efforts of NMENV, and of Maryann McGraw and team in particular. And we appreciate the time George Veni took to share his knowledge with us on April 9.
Karsts
As just noted, the nature of the strata which water flows over and through determines the distribution of surface and sub-surface water and the amount of contamination which is in the water.
Karst features form when carbonate rock (limestone, dolomite, marble) or evaporate rock (gypsum, halite) is dissolved by water. These two factors, type of rock and dissolution, typify karst strata. Karsts are not features created by erosion; they are formed by dissolution. As noted on the following pages, there is a fair amount of carbonate rock at or near the surface in the Black Range, and there is sufficient water available to form karst features (caves, sinkholes, underground streams, and large springs).
There are few reported karst features from the Black Range. Given the amount of mining which has occurred, it is likely that some features would have been encountered if many of them exist.
Rock ranges from impermeable to highly permeable. The permeability of rock is a function of its chemical and physical structure. In the Black Range we have rock strata at both extremes, making for some interesting water-flow questions.
The structure of karst strata (solution openings, below - from Groundwater, a Primer, John E. Moore, American Geologic Institute,1995) allows for the free unfiltered flow of water. Note, “unfiltered” karst water can be easily contaminated. The (relatively) free flow of water which karst rock allows also means that water tends to follow the
strata. Surface drainage topography is not always a significant factor for water- flow through karst strata. That is, if a carbonate stratum, for instance, is found below an area which has several ridges at the surface (each ridge demarking a separate “watershed”) water will flow freely under the ridges, through the carbonate layer, and can easily flow from one watershed to another.
There are many sources of information about karst systems, including www.karstportal.org and the USGS site on karsts in the United States.
The International Year of Caves and Karst -2021 has been extended to 2022 because of the COVID-19 pandemic. The opening video on the home page (link above) is worth the time to watch. This site provides many links to information about cave and karst geology and information about upcoming online events.
It is unlikely that we will ever find cave formations, like the above, in the Black Range. But the complexity of the geology here leads easily to many (as of yet, unanswered) questions about the water we access via wells and the ground water which sometimes runs in our streams. There is a lot more to
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