The papers comprising the various parts of this report contain preliminary results of the U. S. Geological Survey investigations in the U12b.03 and U12b.04 tunnels at the Nevada Test Site, Nye County, Nevada (fig. 1). The geologic studies were undertaken to define the structural, chemical, mineralogic, and some of the physical properties of the tuffaceous rocks that enclose the explosion chambers at the end of each tunnel. The U12b.03 and .04 tunnels are part of the U12b (Rainier) tunnel complex that was driven northwestward from the steep east slope of Rainier Mesa (a prominent topographic feature in the northwest part of the Test Site (fig . 2)). The U12b.03 tunnel trends north from a point about 980 feet from the portal of the U12b tunnel (fig. 3). The U12b.03 tunnel consists of 620 feet of tunnel, two alcoves, and a shot chamber. The tunnel is irregular, ranging from 6 to 10 feet in width, and 6 to 9 feet in height. The shot chamber at the north end of the tunnel is 22 feet on each sidee The vertical and minimum cover over the shot chamber are 610 and 510 feet, respectively.

Nevada↗

USGS1959

Geological Survey investigations in the U12e.05 tunnel, Nevada Test Site

The papers comprising the various parts of this report contain the preliminary results of the U. S. Geological Survey investigations in the U12e.05 tunnel at the Atomic Energy Commission's Nevada Test Site, Nye County & Nevada (fig. 1). Reports on electrical resistivity, natural radioactivity, and heat required to raise the rocks to 100°C will be issued later. A preliminary report on the geologic effects of the Blanca event is being prepared. The U12e.05 tunnel, one of two laterals from the main U12e tunnel, trends west and connects with the main tunnel about U960 feet from the portal (fig. 2). The U12e.05 tunnel was driven for the nuclear test, code name Blanca, which took place on October 30, 1958. Before the explosion, the tunnel was 8 feet high and 8 to 9 feet wide and consisted of 990 feet of workings, a shot chamber, and an alcove (fig. 2). The original shot chamber, at the west end of the tunnel, was 19 feet long, 10 feet wide, and 15 feet high. The vertical and minimum cover over the original shot chamber are 1,150 and 950 feet, respectively. After detonation of the nuclear device in the test, code named Logan, in the U12e.02 tunnel on October 15, 1958, the U12e.05 tunnel, locally, was damaged severely.

Nevada↗

USGS1959

Geological Survey investigations in the U12b.01 tunnel, Nevada Test Site

The U12b.01 tunnel is part of the U12b (Rainier) tunnel system driven northwestward from the east slope of Rainier Mesa (figs. 1 and 2). Geologic and geophysical studies in this tunnel were conducted by the U.S. Geological Survey on behalf of the Albuquerque Operations Office of the Atomic Energy Commission. This report includes a brief description of the stratigraphy and structure, and data on petrology, mineralogy, and chemical and physical properties of the rocks that are exposed in the tunnel. The U12b.01 tunnel trends N. 10° W., and connects with the Ul2b tunnel at about 500 feet from the portal (fig. 2). The U12b,01 tunnel is about 250 feet long and contains an alcove 40 feet long and 20 feet wide, and a shot chamber 17 by 20 feet. The tunnel is irregular and ranges from 6 to 15 feet in width and averages 7 feet in height. Much of the tunnel has been supported using 6-foot steel sets and wood planks for lagging Vertical and minimum cover over the shot chamber at west end of the tunnel are approximately the same, about 295 feet.

Nevada↗

USGS1957