Date of Graduation

Spring 5-2012

Level of Access

Open Access

Degree Name

Bachelor of Arts

Department or Program

Geology

Number of Pages

94

First Advisor

Dyk Eusden

Abstract

The unroofing rate of Mt. Washington, NH is being calculated using apatite fission-track ages (AFT) of thirteen samples along the Cog Railroad on Mt. Washington’s western slope using the relief method. Samples were collected approximately every 500 vertical feet from the summit (6280’) to the base (1770’) of Mt. Washington. The AFT ages determined thus far are: 148.0 ± 15 Ma at 1914 m, 147.2 ± 15 Ma at 1886.7 m, 114.5 +/- 18 Ma at 1743.5 m, 114.4 +/- 12 Ma at 1624.6 m, 119.3 +/- 13 Ma at 1482.2 m, 126.6 +/- 14 Ma at 1392.0 m, 114.4 +/- 16 Ma at 1325.9 m, 118.4 +/- 12 Ma at 1190.6 m, 110.1 +/-13 Ma at 1089.7 m, 102.9 ± 11 at 930.6 m, 96.4 +/- 9 Ma at 842.8 m, 86.4 +/- 8 Ma at 647.1 m and 89.2 ± 10 at 539.5 m. These ages are analogous to ages determined along Mt. Washington’s Auto Road at similar elevations. These values yield an exhumation rate of 0.022 mm/yr between approximately 150 Ma and 80 Ma, which is comparable to the exhumation rate of 0.027 mm/yr calculated for the eastern slope of Mt. Washington along the Auto Road (Roden-Tice et. al., 2011) during this time. Trends in exhumation correlate with with late Cretaceous regional magmatic events associated with local asthenospheric upwelling that reactivated zones of crustal weakness.

Components of Thesis

1 pdf file

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