Annual Fall Field Conference
Geology of the Las Cruces Area
October 24-27, 2018

Every fall since 1950, the Society has held a field conference to some part of New Mexico and, in some cases, to border states. From the beginning, the conference has been accompanied by a guidebook with detailed road logs as well as peer-reviewed papers relevant to the region. These guidebooks remain as invaluable references to the geology of the conference study area and most are available for purchase.

Widespread enthusiasm for the Fall Field Conferences has led to receipt of many proposals for future conferences. Therefore, the schedule of upcoming field conferences is now outlined for the next several years. The field conference venues and names of organizers are listed below. All members are encouraged to volunteer assistance to the organizers or to contribute to the guidebooks. If you live near or are involved with the geology in the vicinity of the future conference sites, please consider contacting one of the organizers.

2018: Las Cruces Country III

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The Las Cruces area is noted for a great variety of geologic features, as well as the unique fauna, flora, and scenery of the Chihuahua Desert.  The region is noted for a wide variety of geologic and geomorphic features as well as the recently-designatedPrehistoric Trackways National Monument (2009) and Organ Mountains-Desert Peaks National Monument (2014).

The last time the NMGS Fall Field Conference was headquartered in Las Cruces was 1998.  Since that time new research has been carried out and new geologic faculty have arrived at New Mexico State University, resulting in many new perspectives on the geologic history of the region. 

Conference Organizers:
Greg Mack, Jim Witcher, Frank Ramos, and Brian Hampton.

Field Conference Overview

All three nights will be in Las Cruces with the headquarters at the Ramada Palms Motel. Conference registration and an ice breaker will be from 6pm-9pm on Wednesday, October 24 in the Rio Grande Ballroom and the Santa Fe Conference Room at the Ramada Palms Motel. Appetizers will be provided in the Rio Grande Ballroom with access to a cash bar.

For the first two days we will use rental vans, whereas private vehicles will be used on the last morning of the conference.

On Thursday and Friday, we will depart from the Ramada Palms at 7:30 AM using rental vans and predetermined high clearance vehicles. We need to maintain the minimum number of vehicles for the Thursday and Friday trips. Individual vehicles will be named so know your specific vehicle name. Vehicles for these two days will line up on the south side of the Ramada Palms parking lot before departing from the northwestern Ramada Palms exit. We will need to get across Valley Dr. heading south (left) when we depart the Ramada Parking lot in order to get on Interstate 10 east (towards El Paso).

On Saturday, attendees will drive their personal cars. Each Saturday site has room for personal vehicle parking, although the Rincon site may need to caravan attendees to the field site from the parking area using 4-wheel vehicles that will be provided (i.e., no need to drive low-clearance personal vehicles to the site itself from the parking area). Saturday departures for home can be made directly from the specific field trip/site chosen after a bag lunch is distributed.

New Mexico saw its first snowfalls over the weekend with snow on many of the central and northern mountains. Be sure to check the weather forecast and pack your layers before you head out to Las Cruces.

Schedule of Stops

Day One: Theme: Cenozoic volcanism.

Stop 1. Evolution of the early Cenozoic Doña Ana caldera: We will examine the 36.1 Ma Doña Ana Rhyolite, erupted during caldera collapse, as well as post-caldera volcanic rocks and a syenite porphyry dike.

Lunch: I-25 rest stop on the route to stop 2.  This stop provides a panoramic view of local mountain ranges.

Stop 2. Point of Rocks: We will take a short traverse to examine ash-flow tuff outflow sheets and interbedded sedimentary rocks of the latest Eocene-early Oligocene Bell Top Formation, as well as the overlying early Oligocene Uvas Basaltic Andesite.

Barbecue: Leesburg State Park

Day Two: Theme: Permian sedimentology; Laramide tectonics, sedimentation, and volcanism; Rio Grande rift structure and sedimentation.

Stop 1. Lucero Arroyo, northern Doña Ana Mountains: On this short traverse we will encounter and discuss: (1) post-early Pleistocene geomorphic surfaces; (2) basal conglomerate of the Pliocene-early Pleistocene Camp Rice Formation deposited in the northern Mesilla half graben; (3) Laramide (latest Cretaceous-Eocene) structure, conglomerates, and andesitic volcaniclastic rocks; and (4) sedimentology of Lower Permian limestones and siliciclastic rocks deposited along the western edge of the Orogrande Basin during the Ancestral Rocky Mountains tectonic event.

LunchFort Selden Historical Site.  Time will be made available for quick viewing of the displays in the visitor’s center and the ruins of the fort.

Stop 2Southern Robledo Mountains, a young fault block of the southern Rio Grande rift: The main focus will be on the relative timing of the Robledo range boundary fault, intra-uplift faults, intrusion of basalt, and deposition of Camp Rice conglomerate perched on the footwall block. We also will see evidence of erosional scarp retreat and post-late Pleistocene reactivation on the range boundary fault.

Banquet.  Ramada Inn.

Day Three: at time of registration, participants will select one of following three trips.

  1. Late Pliocene geothermal opal and calcite beds in axial-fluvial sediment of the Camp Rice Formation in the Rincon Hills (leader: Greg Mack).
  2. Early Cenozoic igneous activity in the Organ Mountains at Dripping Springs (leaders: Frank Ramos, Brian Hampton, Bill Seager).
  3. The Radium Springs Geothermal System and the Masson Geothermal Greenhouses (leader: Jim Witcher).

Future Conferences:

2018: Las Cruces

2019: Raton

2020: Mt. Taylor

If you have an idea for a future field conference, please contact the President of the NMGS.

Photos From Past Fall Field Conferences

Everyone is invited to share their best digital photos of past conferences with the rest of the Society membership. Please contact the society webmaster via the 'comments' link below.