Paleo-environments:
The formation of Mount Garibaldi volcanic field during the Pleistocene and Holocene gives this region a complex geological setting. A total of eight lava flows ranging in age of 260,000 years to less than 10,000 years B.P. cover the study area (Brooks and Friele 1992; Green et.al 1988 and Green 1991; Mathews 1951 and 1952).
Glaciation and de-glaciation of Wisconsinan ice masses in the Coastal Mountain Range was complete by 10,000 years B.P. (Armstrong 1981). Mass wasting occurred after de-glaciation. The scouring out of bed rock by glacial masses left a barren and unstable landscape. The steep and rugged appearance of the Coast Mountains are due to these glacial activities (Ryder 1981).
In addition to glacial processes, the development of the Mount Garibaldi strato- volcano and surround area can be attributed to a series of unique events. A number of violent eruptions of Mount Garibaldi took place at the end of the Wisconsinan glaciation. These eruptions resulted in the formation of a solid dacite core. This core is surrounded by a series of lava flows and tuff/ breccia cones. The upper cone sections of Mount Garibaldi protruded above the glacial ice yet only sections were supported by a solid base of rock. The western flank of the volcano was supported only by glacial ice. De-glaciation caused the western flank of the volcanic cone to collapse. Large amounts of volcanic sediments from the western flank of the volcano are reworked into till and delta deposits on the lower Squamish and Cheakamus river valley floors. More recent Neo-glacial events have reworked some of the original deposits, yet not to the large extent of the Wisconsinan maxima (Mathews 1951; 1952).
Early Holocene warming termed the Hypsithermal interval, ca. 8,000-6,000 radiocarbon years B.P. This warm period extended tree lines up slope 60 to 120 meters (Clague and Mathews 1989; 1992; Douglas 1972; Evans 1996).
At the end of the warm Hypsithermal interval, cooler and wetter conditions have prevailed (Clague and Mathews 1989; 1992; Ryder and Thompson 1986). The onset of this cooler and wetter pattern brought about further landscape change. Sub-alpine and alpine glaciers in the Coast Range expanded. These neo-glacial conditions are summarized by Porter and Danton (1967), while more recent regional research can be found in Ryder and Thompson (1986). In summary the results of these neo-glacial studies can be summarized as follows;
1) The Garibaldi Advance
6,000-5,000 radiocarbon years B.P.
2) The Tiedemann Advance
3,300-1,900 radiocarbon years B.P.
3) and the Little Ice Age
900-200 radiocarbon years B.P.
The advance and retreat of these events are reconstructed by radiocarbon dating samples of overridden or washed out wood debris. The logic involved is as follows; the radiocarbon date offers the event of interest, i.e. the over ridding of a live tree by expanding glacial ice. Remains of older neo-glacial ice expansions are difficult to detect because of later subsequent ice advances wiping out moraines and overridden plant debris used to reconstruct these events (Clague and Mathews 1989;1992; Ryder and Thompson 1986; Porter and Danton 1967).