It is believed that this valley asymmetry is related in part to sunshine or “insolation” dynamics. The Pine Barrens experienced extended cold periods for the last
couple of million years. During frigid episodes the ground remained frozen late into the summer (deep seasonal frost) or remained frozen all year round (permafrost). Although air temperatures were quite cold, the sun’s rays were still warming. Radiant energy was strong enough to thaw the ground in direct exposure to the sun, especially when snow cover was thin.
North- and East-facing slopes are often steeper here because they received the least amount of thawing sun. South- and West-facing slopes received the most amount of radiant energy, so they thawed and wasted away much more quickly than North- and East-facing slopes. This effect is not very well pronounced in the Arctic since there the sun’s angle is very low and not very intense. That is not the case in the Pine Barrens. It is believed that in frozen mid-latitude South Jersey the resultant slope asymmetry is well expressed because of insolation (Demitroff, 2007: 82–83; French
et al., 2007: 54).