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pg 002: Geology of the Marathon region, Texas Publication 6445288

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INTRODUCTION

Location

-This report deals with the geology of the Marathon region, which lies in the northern part of Brewster County, in western Texas. Particular attention is paid to the geologic features exposed in the Monument Spring and Marathon quadrangles, which extend across the central part of the region and cover an area more than 30 miles east and west by 20 miles north and south. In order to complete the description of the Marathon region, some of the stratigraphic and structural features to the north and south of the two quadrangles are also noted.

Figure 1.-Index map of trans-Pecos Texas showing location of Marathon Region. The shaded is that covered by the detailed geologic map (pl.24).

The region is crossed from east to west by the main line of the Sunset Route of the Southern Pacific Railroad, upon which, about halfway across the area, is the village of Marathon, the only settlement. (See fig. 1.)

Previous work

-The Marathon region was mentioned in 1890 by Von Streeruwitz, who noted northeastward trending ridges south of Marathon composed of "quartz and quartzite, strongly metamorphosed limestone, and semifused siliceous conglomerations." He mistakenly correlated these with the Cretaceous rocks cropping out to the east and west, which he thought had here been "fused and thrown up by protrusive volcanic rocks."

A good description of the geologic features of the area was given by Hill in 1900. After noting the character "

Von Streeruwitz, W. H., Report on the geology and mineral resources of transPecos Texas: Texas Geol. Survey 2d Ann. Rept., for 1890, p. 686, 1891.

Hill, R. T., Physical geography of the Texas region: U. S. Geol. Survey Top. Atlas, folio 3, p. 4, 1900.