Taking Inventory at Oregon Caves
Effective monitoring, mitigation, and restoration of important resources can be done only if good inventories exist. Few caves, however, have good inventories. This is because many of them are very diverse, often difficult to access, and represent an alien environment to most people.
To close this data gap, volunteers from EARTHWATCH helped National Park Service staff at Oregon Caves complete the first comprehensive inventory of any large federal cave in the United States. One of the difficulties in conducting inventories is that definitions sometimes set arbitrary limits, but this one is flexible enough for use in other caves. As a result, inventory items for Oregon Caves were developed from a standardized 400 word glossary which caters to site-specific needs, yet allows for comparisons of those features that many caves have in common.
Several important correlations became apparent during the inventory. One of them involved finding the largest passages correspond with fault directions and the direction water flows the fastest, or steepest hydraulic gradient. This helps explain why Oregon Caves is so big in comparison to nearby caves.
Inventory teams also found marked breaks between the dimensions of some cave features which allow more sophisticated comparisons to be made. Similar features, such as parallel ridges among microgours in flowstone and those occurring in rimstone dams, can be separated by breaks in averaged measurements or by different distributions. For example, microgours usually range up to one quarter of an inch in size while the low end measurements of rimstone dams are about one inch. Consequently, flowstone and rimstone can be better indicators of localized differences in the cave’s hydrology. This is possible because flowstone is formed by water slowly seeping between rock layers in contrast to rimstone dams following stream flow.
More information is now at hand concerning the magnitude of direct human impacts on cave formations. “Cave slime” are actinomycetes bacteria, which appear as small white spots on walls. This bacteria is less evident along the tour route, leading to the supposition that bacteria feeding on lint from clothing may be outcompeting cave slime. There are also fewer white formations on the tour route than elsewhere in the cave. Skin oils and smoke from torches decades ago have certainly contributed to this situation.
Now that the inventory has provided some insight on human impacts at Oregon Caves, cleaning and repair of formations has begun. Tons of rubble from previous trail building efforts have already been removed. These measures are part of a restoration effort and will enhance future visits to the cave.
