flows on Hawaii Island. B.Small-eyed, big-eyed hunting spider (Lycosa howarthi), living underground in young volcanic substrates on Hawaii Island. These two species differ only in their adaptations to their environments. C. No-eyed, big-eyed hunting spider (Adelocosa anops) from remnant lava tubes on Kauai Island. This species evolved its adaptations to caves independently of L. howarthi (B), via a different ancestor. (Photos by W.P.Mull)

doi:10.4324/9780203483855-190

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flows on Hawaii Island. B.Small-eyed, big-eyed hunting spider (Lycosa howarthi), living underground in young volcanic substrates on Hawaii Island. These two species differ only in their adaptations to their environments. C. No-eyed, big-eyed hunting spider (Adelocosa anops) from remnant lava tubes on Kauai Island. This species evolved its adaptations to caves independently of L. howarthi (B), via a different ancestor. (Photos by W.P.Mull)

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ABSTRACT

FRANCIS G.HOWARTH See also Colonization

Works Cited

Further Reading

To build good and safe highways on karst, and at the same time to identify and protect the natural heritage, it is necessary to take into account the special features of karst at the planning stage and in monitoring of construction (Knez & Slabe, 2001). Hence, karst

geomorphologists, hydrologists, and speleologists, frequently contribute to decisions on the choice of right-of-way, methods of construction, the stabilizing of caves, and costbenefit analyses of different methods of construction. Decisions on the best alignment for a highway through karst should be preceded by a complete study of the karst, considering data from various sources (e.g. a database of cave and water features) together with targeted fieldwork. As a rule, the more important karst features, whether surface landforms or caves and waters, are best avoided. The presence of voids in the karst rocks and the permeability of the surface, which can both influence the construction of highways, may be deduced, in part, from geological and geomorphological mapping, speleological investigation, and study of aquifer characteristics. The presence of voids and rockhead features may also be revealed by core drilling. Geophysical approaches such as geoelectric and ground-penetrating radar surveys, seismic reflection and refraction profiling, tomography and microgravimetry surveys may also be used (see Geophysical Detection of Caves and Karstic Voids). However, whether regarding the rock, the hydrogeology and climate, or the karst cover, each individual karst region has special characteristics and it is best to adapt the approach to these factors in each case. These methods are used before construction as well as during construction when the karst surface has been stripped and levelled and caves have been exposed.