Legacy databases and GIS: a discussion of the issues illustrated by a case study of archaeological site data from southeast Alberta,Canada

Many institutions and agencies are currently faced with the issue of geographic information systems‐enabling legacy databases. The problems can be acute for data sets that have been compiled through many years, using different standards and levels of recording. To explore these issues further, we report on a data quality assessment undertaken in 2002 for a subset of the archaeological site database of the province of Alberta, Canada. Our work shows that positional ambiguities in the data set can be highlighted and corrected by relatively straightforward procedures. This case study also provides an indication of the amount of work effort that will be involved in validating or ‘cleaning up’ data sets so model results and analyses undertaken with them are more reliable.     

Pollen evidence for major shifts in forest composition since the mid‐nineteenth‐century in the vicinity of Sudbury,Ontario

Numerous anthropogenic stressors have impacted the region surrounding Sudbury, Ontario, leading to pronounced vegetation and landscape change. Few long‐term records exist to understand the nature or timing of this change. We use pollen analysis from radiometrically dated sediments of Clearwater Lake to compare pre‐ and post‐settlement vegetation. Beginning ～1850 CE, the record shows major shifts in forest composition, coincident with settlement and the beginnings of lumbering. These changes are unprecedented for the past ～5000 years, and consist of increases in diversity and abundance of deciduous tree taxa and herbaceous disturbance indicators. While evidence of mining appears as early as 1900 CE, little effect is seen in the pollen record until ～1930 CE, when sedimentation rates increased and acidification of the lake also began. At this time, further increases in palynological disturbance indicators and minimum sediment organic matter levels indicate the period of maximum vegetation loss. As a result of reduced emissions since the 1970s, water quality began to improve in Clearwater Lake and there are some decreases in the abundances of shade‐intolerant disturbance indicators in the pollen record. However, the fact that the pollen assemblages do not resemble those prior to 1850 suggests lasting vegetation changes.