Postcards From the Field

Studying carbonatites in the Lemitar Mountains, north of Socorro, New Mexico during a pandemic! Carbonatites are carbonate-rich rocks containing more than 50% magmatic carbonate minerals, less than 20% SiO₂, are of magmatic derivation, and typically found in zoned complexes consisting of alkaline igneous and/or carbonatite stocks, ring dikes, and cone sheets.

New Mexicans are no stranger to flash floods. The arroyos around the state often flow during our annual summer monsoon; water quickly collects in dry channels, bringing rock and sediment along with it. Predicting floods in arroyos is still a difficult task: at the Arroyo de los Pinos sediment monitoring station, we are measuring these flows just west of Socorro, NM.

Faults are fractures in Earth’s crust where blocks of rock move in opposite directions relative to one another. The Jornada fault, pictured here near Radium Springs (north of Las Cruces, New Mexico), beautifully displays the juxtaposition of units from fault slip.

Well-developed growth rings in fossil trees in the Ojo Alamo Sandstone, like those seen to the right of the orange notebook in this photograph, likely indicate pronounced annual seasonality of temperature or precipitation when the tree was growing.

"I have been working along Milligan Gulch with Kevin Hobbs and Kristin Pearthree (both of the NM Bureau of Geology) to make a geologic map of the Fort Craig quadrangle. Milligan Gulch is the canyon immediately south of the dirt road to Fort Craig, located about 30 miles south of Socorro. This canyon has a fantastic set of terraces, which can be correlated to terraces flanking the west side of the Rio Grande..."