Even though this volcano has been dormant for around 10,000 years, when it erupted it spread a lava flow that reached over 100 miles in length, creating the Zuni-Bandera Volcanic Field. More recent eruptions (within the last 3000 years) have increased the depth and reach of the field. You can explore the Zuni-Bandera field at El Malpais National Monument nearby.
Blasters saw cinder cones, spattercones, lava vents, lava tubes, and lava caves (some with perpetual ice and some with bats) as we explored the Bandera Crater.
From the NM Bureau of geology & mineral resources website: (
visit link)
"Geologic Background
Zuni-Bandera Volcanic Field
The Zuni-Bandera volcanic field, in northwest New Mexico, has had many episodes of basaltic eruptions over the last million years (Laughlin et al., 1993). The youngest lava flow in the field is the McCartys flow, which is only 3000 years old, one of the youngest volcanic features in the 48 contiguous United States! The Zuni-Bandera volcanic field has produced many basaltic lava flows, some with a-a characteristics, and some that are paheohoe. There are also a number of well-preserved cinder cones that can be visited, as well as many lava tubes, some of which contain perennial ice. The Zuni-Bandera volcanic field is an excellent site for studying physical volcanology of basaltic magmatic systems.
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Features
The Zuni-Bandera volcanic field consists of a large number of basaltic lava flow and cinder cones, and exhibits a number of striking features of hawaiian-style volcanism. Pahoehoe and a-a lavas are both represented, along with well-developed lava tube systems.
Nichols (1946) mapped and catalogued the geomorphic features of the apparently-young McCartys basalt flow and recognized many features of Hawaiian-style volcanism, including pahoehoe flow patterns, small spatter cones, gas cavities, large wedge-shaped cracks, collapse depressions, large pressure ridges and tumescences. These types of features are also present in other, apparently-older flows, although in some cases are obscured by erosion. At least 100 vents have been recognized in the volcanic field (Luedke and Smith, 1978), and the flows cover a large aerial extent of 2,460 km2. Combined flow thickness is as great as 145 m in some places, and the total volume of all flows is at least 74 km3 (Laughlin et al, 1993).
McCartys Flow
McCartys flow is the youngest basalt flow within the Zuni-Bandera volcanic field. Its source is a low shield volcano located about 40 km south of the intersection of I-40 and NM-117. A small cinder cone about 8 m high sits on top of this broad shield. Although some of the lava flowed southwestward 8 to 9 km, most followed the preexisting drainage and flowed northward about 40 km before turning to flow eastward 10 km down the Rio San Jose valley. The McCartys flow overlies older basalts of the Zuni-Bandera volcanic field and Holocene alluvium.
The McCartys flow is typically a vesicular, porphyritic basalt. Carden and Laughlin (1974) examined chemical and petrographic variations along the length of the flow and reported that within 4 km of the source the basalt is characterized by plagioclase phenocrysts 0.20 to 1.5 cm in length. At greater distances from the source, large plagioclase phenocrysts are absent and olivine phenocrysts are present. Plagioclase is the dominant mineral in samples of McCartys flow.
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Bandera Crater Flow
The Bandera flows originated from Bandera Crater, a double cinder cone about 150 m high and 1 km in diameter. The eruption of Bandera Crater and its associated flows was the second youngest volcanic event in the ZBVF. Like many other cinder cones in the ZBVF, Bandera Crater is breached to the southwest, probably due in part to local prevailing winds. A large lava tube, intermittently collapsed, extends about 29 km south from the breach in the crater wall and a commercial ice cave is located in a collapsed portion of the tube near the Candelaria Trading Post. Causey (1970) recognized seven stages in the development of Bandera Crater and its associated flows, culminating in the eruption of the black cinders that cap the cinder cone and blanket the hills to the north. . . . Both aa and pahoehoe surfaces are common on the flows.
Five different dating techniques have been used to date the Bandera flows or to constrain their ages. These ages were suspected of being too old due to the possible prescence of excess Ar in the samples. Since then, charcoal collected from under the cinders, and presumably carbonized by the eruption, yielded ages of 10.05-10.07 ka. In summary, the Bandera crater cinders and lava flows probably erupted around 10,000 years ago."