R E L I C D U N E F I E L D S I N N O R T H A M E R I C A

Photograph: kcspor!our

Sand and loess deposits in the United States Sun and Muhs 2007

Global distribution of aeolian sand Sun and Muhs 2007

Lt. G.K. Warren’s sketch of the Nebraska Sand Hills, 1855

Source: Stephen Wolfe

“...the men and horses were in great want of water, and the heat was very great while travelling through miles of burning sand.”

Captain John Palliser, 1863

Source: Hughenholtz et al., Aeolian Research (2010)

Were these dune fields more active prior to the 20th century?

Photograph: Stephen Wolfe

Photograph: baba1627

Impurities or defects in this structure can act as “traps” for free electrons.

free electron

The rate at which free electrons are produced, and traps are filled, is proportional to:

• the amount of radioactive elements in the minerals being dated

• the amount of radioactive elements in their surroundings.

Photograph: Ben+Sam

Photograph: Pandiyan

Source: Wolfe et al., Geographie physique et Quaternaire, 2002

Photograph: Stephen Wolfe

Stephen Wolfe Geological Survey of Canada

Source: Stephen Wolfe

Source: Wolfe et al., Geographie physique et Quaternaire, 2002

Source: Wolfe and Hughenholtz, Geology, 2010

Source: Stephen Wolfe

Light Detection and Ranging (LiDAR)

Source: Wolfe and Hughenholtz, Geology, 2010

barchan dune

parabolic dune

back ridgeresidual

dune ridges

Parabolic dunesPhotograph: Shooting Chris

Barchan dunesPhotograph: Ron Scho!

S TA B L E I S O T O P E S I N P A L E O C L I M AT O L O G Y

less O18“depleted”

more O18“enriched”

more O18

“enriched”

less O18“depleted”

Source: Jouzel et al., Journal of Geophysical Research, 1994

Source: Jouzel et al., Journal of Geophysical Research, 1994

“light”

“heavy”

“more positive” δO18 = “heavy” = “enriched”for example, ocean water

“more negative” δO18 = “light” = “depleted”for example, glacial ice

Source: Bowen and Wilkinson, Geology, 2002

δO18 in precipitation