CH06: Past Terrestrial Response

FIGURE 6.1 Pangaea (a), Laurasia and Gondwanaland (b). Source: (a) Courtesy of Canadian Geographic. (b) From Wikimedia Commons.

FIGURE 6.2 Distribution of forest types, 90 million years ago. Warm rain forest existed at high latitudes in the warm climate of this period. Global mean temperature was much warmer at this time than at present (see inset). Source: Adapted from Bush et al. (2007).

FIGURE 6.3 Distribution of warm rain forest and warm seasonal forest 55 million years ago, near the early Eocene Climatic Optimum (inset). Source: Adapted from Bush et al. (2007).

FIGURE 6.4 Distribution of warm rain forest and warm seasonal forest 30 million years ago, just after the global cooling associated with the formation of Antarctic ice sheets (inset). Source: Adapted from Bush et al. (2007).

FIGURE 6.5 Distribution of warm rain forest and warm seasonal forest 15 million years ago. Source: Adapted from Bush et al. (2007).

FIGURE 6.6 Present distribution of warm rain forest and warm seasonal forest. Source: Adapted from Bush et al. (2007).

FIGURE 6.7 The uplift of the Andes. Effects of the uplift of the Andes are shown on river courses, wetlands, and lowland forest extent from 65 million years ago to the beginning of the Pleistocene 2 million years ago. Note the large wetland (B, C) prior to the rise of the northern Andes and the shift in drainage toward the Amazon (B, C, D). Source: Hoorn et al. (2010). Reprinted with permission from AAAS.

FIGURE 6.8 Present and last glacial maximum vegetation formations and biomes. Pollen analysis can be used to assign vegetation formations and biomes for past climates. The top panel shows vegetation formations and biomes inferred from analysis of current pollen rain. The middle panel shows the actual current vegetation formations and biomes. The bottom panel shows vegetation formations and biomes for the last glacial maximum, inferred from pollen data. Source: Jackson et al. (2000).

FIGURE 6.9 Drilling a sediment core. Paleoecologist Nicole Sublette lowers a coring device to a lake floor in the Peruvian Andes with help from Eric Mosblech, a teacher volunteer participating in a field expedition as a means to improve high school curriculum development. The sediment in this core was dated based on annual variations in deposition, and the pollen in each strata counted under a microscope to assess the vegetation surrounding the lake at the time the sediment layer was deposited. Source: Courtesy of Mark Bush, Eric Mosblech, and Nicole Sublette.

FIGURE 6.10 Macrofossil and pollen records near the Laurentide Ice Sheet. Trace pollen amounts interpreted as wind-blown input from distant forests in many studies may actually represent pollen micropockets near the ice sheet. Macrofossil records indicate the presence of forest trees near the ice sheet even in times for which little pollen has been recorded from these locations. Source: Jackson et al. (1997).

FIGURE 6.11 Younger Dryas temperature fluctuation. The Younger Dryas is a millennial-scale cool period (shaded area) initiated by a rapid cooling and ended by rapid warming. Source: Redrawn from Alley (2007).

FIGURE 6.12 Dryas Octopetala, known commonly as Mountain Avens or White Dryas. Source: From Wikimedia Commons.

FIGURE 6.13 Greenland ice core. Source: Courtesy of NASA/JSC.

FIGURE 6.14 Vegetation change in tropical Southeast Asia. Vegetation types (horizontal bars) and limits (vertical bands) inferred from pollen analyses for sites in Southeast Asia. Source: Flenley (1998).

FIGURE 6.15 48,000 years of change in the tropical Andes. Paleotemperature and paleoelevation inferred from pollen spectra from Lago Consuelo, Peru. Color indicates the probability that a sample came from that elevation or temperature (blue, low; orange, high). Note that time runs right to left in this figure. Source: Bush et al. (2004). Reproduced with permission from AAAS.