El Malpais National Monument
One of the oldest eruptive centers at the El Malpais National Monument, the El Calderon area offers above ground explorations of sinkholes, aspen groves, El Calderon crater and lava trenches. Underground explorations take you into Junction Cave, a 3,000-foot-long lava tube. To venture underground, and for your safety, take several light sources, boots, hat, gloves and protective clothing.
Heading west on SR53, turn south soon after mile marker 66, approximately 20 miles from I-40. The first 1/4 mile is suitable for all vehicles. Other area roads require high clearance. Please stay on designated roads. Vehicle travel in the El Calderon area is discouraged when roads are wet.
El Calderon Crater & Flow
El Calderon was a rapid, fluid flow. This is evident especially by the long distances traveled by the flow. The gentle, rolling, grass-covered basalt hills under and around I-40, near Grants, originate from the El Calderon vent 20 miles away. Much of this flow is covered by later flows. Cerro Bandera and Cerro Rendija are similar flows considered to be concurrent with El Calderon dating back somewhere between 150 to 800,000 years old.
This crater and its flow are among the oldest of the flows in the El Malpais National Monument. The relative age of this flow can be seen by its dull, weathered look and by the amount of extensively vegetated soil that covers much of the flow.
Junction Cave is actually part of a lava tube system that borders the El Calderon flow. It originates about 3 miles northwest from the Twin Craters cinder cones. This tube extends approximately 3,000 feet over ceiling blocks that fell as the tube cooled, shortly after the eruption ceased.
Lava tubes are the pathways that lava travels downslope. The lava exposed to the air cools rapidly, creating a crust that insulates the molten lava inside, which continues to flow. When the magma chamber empties and the flow diminishes, the remaining lava flows out of the tube, leaving a flat-floored tube with an arched ceiling.
Because most lava tubes lack the necessary ceiling support, portions fall or collapse creating twisted rubble-filled trenches where tubes once were.
Mexican Freetail Bat
A Mexican freetail bat colony migrates between the caves in this area and somewhere in Mexico. Flights can be observed at dusk during the summer from the knoll above the bat cave entrance.
Because of very dangerous health risks to humans and the disruption to the bats, do not go into any designated "bat cave." If you are in a cave and come across bats, do not shine lights at them or otherwise disturb them. These caves are their homes.
Details mentioned in this article were accurate at the time of publication