ROCKS, MINERALS & FOSSILS

New Mexico is ranked as follows:

• third in the nation in natural gas production (1.70 trillion cubic feet) and second in reserves
• seventh in oil (71.6 million barrels)
• thirteenth in coal (24.6 million tons)
• first in potash (1.27 million tons)
• first in zeolite and perlite (approximately 500,000 tons)
• third in copper (564 million pounds)
• second in carbon dioxide (145.8 billion cubic feet)

(from New Mexico Bureau of Mines & Mineral Resources). This high degree of mineralization provides rock hounds with a large array of rocks and minerals to observe and collect.

ROCKS

A rock is, in general, an aggregate of minerals.  Some rocks consist of a single mineral such as limestone.  All three types of rocks can be found in Eddy County as follows:

Igneous rocks are formed from a molten state after cooling and solidification.  Rocks that do not melt but become heated and the crystalline structure of these rocks change are called Metamorphic rocks.  These types of rocks are generally formed in mountain uplift areas.

Sedimentary rocks are formed at low temperatures and pressures at or near the earth’s surface by transportation, deposition, and eventual accretion of grains of material originally eroded from previously existing rocks, or as a result of precipitation of minerals from water.  Virtually all fossils are found in sedimentary rocks.

MINERALS

In general, a mineral is a homogeneous, naturally occurring inorganic solid.  The chemical composition of minerals vary only slightly and they have a characteristic crystal structure.  Over 2500 minerals have been described.  They are generally recognized by distinctive characteristics such as crystalline structure, hardness, and cleavage.  

The hardness scale used by geologist is called the Mohs' Scale.  It matches various minerals as follows:

Some minerals that can be found near The Ranch include the following:

This is not an exhaustive list by any means.  The igneous and metamorphic rocks of the mountains to the west of The Ranch offer a wonderful opportunity to find beautiful crystals of quite a number of minerals.

Click on the small thumbnail photographs below to enlarge the image.  Use your back button to return to this page.  All are from New Mexico with the exception of the Calcite crystal (Mexico).

Azurite - Tourmaline	Barite	Calcite	Cerussite - Galena
Chalcopyrite	Copper - Native	Fluorite - Barite	Fluorite - Quartz
Gypsum - Selenite	Halite	Halite	Linarite
Malachite - Azurite	Quartz, Specular	Quartz, Smoky	Sphalerite

FOSSILS

Fossils are generally found in Sedimentary Rocks.  The Ranch is located on a sedimentary plain of alluvial origin (deposit of sand or mud formed by flowing water) but very few fossils will be found therein.  The hills in the distance; however, provide a wealth of fossils for much of it was a part of the large Capitan Reef.  Fossils that can be found in these rocks include the following:

Phylum	Group	Illustration
Coelenterata	Corals
Brachiopoda	Brachiopods
Mollusca	Pelecypods
Mollusca	Gastropods
Mollusca	Ammonites
Echinodermata	Crinoids	Calyx Stem
Echinodermata	Echinoids
Arthropoda	Triobites

GEOLOGY / PHYSIOGRAPHY

New Mexico is located on the eastern edge of a tectogenic region (mountain-building) that became active during mid-Cenozoic time in a series of events known as the Laramide Revolution.  The western two-thirds of the state has been profoundly affected by these forces in the form of block faulting, vulcanism, and regional uplift, while the eastern third where The Ranch is a relatively level surface composed of sedimentary by-products of western diastrophism.  The Rio Grande Valley divides the region into eastern and western sections.  Western New Mexico is a land of mountains, mesas, plateaus, and intervening basins and valleys while Eastern New Mexico is a region of relatively level plains.  

The Ranch is located in Eastern New Mexico on a recently developed alluvial plain (Holocene - see Geological Time Scale below).  The hills to the south and east of The Ranch are composed of formations from the Permian period when the area was covered by a coral reef at the edge of a quiet, shallow sea in what is termed The Delaware Basin.  Coal deposits along with much of the oil and gas produced in the area originated in the rocks of this period and the other periods of the Paleozoic era.  At the end of the Paleozoic era, the sea receded and a large inland sea was formed in west Texas and our portion of southeastern New Mexico.  As the sea(s) dried, the evaporating water left wide-spread deposits of salty, gypsum-rich Permian Basin deposits.  These deposits to the east of Carlsbad are rich in potash that is now mined extensively for use in fertilizers.  Potash mines in this area are from 900 to 1800 ft underground.

Near The Ranch, oil and gas are produced from the underlying Permian limestone.  The wells with dinosaur pumps are oil wells while those with stacks of valves and gauges known as Christmas Trees are generally gas wells. The porous Permian rocks also carries water from the Sacramento Mountains about 60 miles west.  The nearby town of Artesia got its name from the artesian springs that emanate from these rocks. 

Guadalupe Ridge to the southwest of The Ranch is in reality an ancient coral reef known as the Capitan Reef for the peak at the end of the mountains.  Fossils abound in this reef including crinoids, brachiopods, corals, bryozoans, and gastropods.  The Sitting Bull Falls day-trip suggested below takes you to parts of this reef where you can observe the remains of these animals.

Geological Time Scale

Surface formations in the vicinity of The Ranch.
See color key on the Geological Time Scale above.
Adapted from Peter A. Scholle, 1980 and 1992.

SUGGESTED GEOLOGICAL DAY TRIPS

The Bureau of Land Management allows the removal of 250 lbs of rock or 25 lbs of minerals/crystals.  We are not allowed to dig for rocks or crystals.  

Each of the following field trips are available in black type with a white background and without photographs to facilitate printing and use as a log while traveling in your vehicle.  Click on the Trip Number to bring up this version of the log.

Pecos diamonds

TRIP 1. Chalk Bluff Road - Pecos Diamonds, well formed double-ended quartz crystals, abound along the Pecos River in the weathered Permian rocks.  They are particularly abundant on the slopes of the hills forming the horizon east of The Ranch, just across the Pecos River.  You can reach the collecting area as follows:

Pecos Diamonds collecting site.

Further along the ridge of these hills, you can find other good collecting sites in the Permian limestone rock.  When you get to a good collecting site, there should be a lot of glistening crystals on the ground resembling an area of broken glass.  We have particularly good luck collecting in wash (drain) areas.  A geologist at the Bureau of Land Management in Carlsbad told us of a collecting site on private land that has yielded crystals of several inches in length and diameter!  

Pecos Diamonds in matrix rock.

Pecos Diamonds scattered on ground.

TRIP 2.  Sitting Bull Falls - The following field trip is based for the most part on a field log presented by Peter A. Scholle entitled Dark Canyon-SittingBull Falls-Rocky Arroyo contained in his work An Introduction and Virtual Geologic Field Trip to the Permian Reef Complex, Guadalupe and Delaware Mountains - New Mexico and West Texas.   

SUGGESTED LINKS AND REFERENCES

References

Chronic, H. 1987.  Roadside Geology of New Mexico.  Mountain Press Publ. Co., Missoula, Montana. 

Crow, M.  1995.  The Rockhound’s Guide to New Mexico.  Falcon Press Publ. Co., Helena, Montana.

Kimbler, F. S. and R. J. Narsavage Jr. 1981.  New Mexico Rocks & Minerals.  Sunstone Press, Santa Fe, New Mexico.

Kues, B.S. 1982.  Fossils of New Mexico.  Univ. New Mexico Press, Albuquerque, New Mexico.

Mitchell, J. R. 1987.  Gem Trails of New Mexico.  Gem Guides Book Co., Pico Rivera, California.

Links

New Mexico Bureau of Mines & Mineral Resources

An Introduction and Virtual Geologic Field Trip to the Permian Reef Complex, Guadalupe and Delaware Mountains, New Mexico-West Texas

The New Mexico Museum of Natural History and Science