- Author
- Catts, Wade P.
- Date of Publication
- 1997.
- Call Number
- 974.8011 C369
the ice into central Pennsylvania (Clark and Ciolkosz 1988; Martin 1958;
Watts 1983). Vegetation zones shifted northwards rapidly as the ice melted and retreated
(Delcourt and Delcourt 1987; Gaudreau 1988; Webb et al. 1987), but spruce trees were common
in the Middle Atlantic region until about 1