Lake Bonneville and Estimates of Upper Mantle Viscosity

Kevin Kwong & Glynis Jehle

Keith Vaught, “Ancient Shoreline” via Flickr, August 28, 2011 , < http://www.flickr.com/photos/hiker56/444876892/>

Water

Image from GEOCACHING

Passey 1981

Shoreline Measurements Reflecting Isostatic Rebound

Crittenden 1963

Elevations of Bonneville and Provo Shorelines

North and South Profile West and East Profile

Passey 1981 Passey 1981

Calculating Viscosity is the viscosity of the substratum in poises

f represents the dimensions of the load

ρ = 3.4 g cm/3, the density of the substratum

g is the acceleration caused by gravity on earth, 9.8 m/s2

k = 1/Tr , time 0f rebound is 4000 yrs

Solving for viscosity gave a value of 0.96 x 1021 poises, or 1021 poises