Aeromagnetic map of the Wheeler-Latir Costilla section of the Sangre de Cristo Mountains in New Mexico
— Lindrith Cordell

An aeromagnetic survey covering about 11,000 km² in northern New Mexico has recently been completed through a cooperative project between the New Mexico State Bureau of Mines and Mineral Resources and the U.S. Geological Survey. At this writing only the data from about the eastern one-third of this project have been reduced and contoured (Fig. 1). The entire project area, which will extend westward to 106° 30' west longitude, is being mapped at a scale of 1:62,500.

 

The purpose of this note is to call attention to the existence of the aeromagnetic data and also to certain regional features evident on small scale aeromagnetic contour maps. Detailed interpretation must be based on the larger-scale maps because of the complexity of the geology and the effect of topography. Rugged terrain exists in much of the area surveyed, producing spurious magnetic anomalies due not to variation in lithology, but to variation in distance between the magnetic source rocks and the magnetometer. Terrain-effect anomalies are evident at Latir Peak, Wheeler Peak, Baldy Peak and elsewhere (Fig. 1, p. 282). Many of the anomalies that are obviously related to mountain tops extend beyond the mountain tops, indicating that the anomalies are probably also related to lithologic variations, with the terrain effect superimposed. This is reasonable inasmuch as the terrain itself may be related to lithology.