Earth Evolution Sciences – serie

Within the last decade or so, the accelerated growth of Nigeria in the fields of urbanisation, population, business as well as industry has led to some attention in assessment of available water resources in various parts of the country. Many workers (du Preez and Barber, 1965; Jackson, 1978; Faniran and Omorinbola, 1980; Ofodile, 1983; Egboka, 1983; Akujieze, 1984; Ogbukagu, 1984; Uma, 1984) have made significant contributions in this area. Water is important because the attainment of the goals of any society as well as the health and well-being of the population depends on a plentiful and reliable supply of this natural resource. Water forms an indispensable input into economic activities such as commerce, tourism and industry. The results of the various researches have revealed that water resources (surface and groundwater) in many parts of the country, especially the southern part, are more than adequate to meet any demand and only need development. A complete appraisal of available water resources is often best accomplished when aspects of water quality are included. This is because in a planned water supply system, quality constraints and requirements dictate the sources of water allocated to various stages. A public water supply, though contributing greatly to the human health and well-being, can also be a vehicle for spreading disease if not properly handled. In this paper, water quality of selected water resources (surface and groundwater) in some parts of Imo State, Nigeria are reported and suggestions advanced for their healthy untilization.

The Cretaceous tectonics of the South American Andes region is the subject of this monograph written by contributors in the field of geosciences worldwide. The theme is not only of interest from an academic point of view given the vast array of tectonic processes which governed the evolution of the Andes towards the end of the Mesozoic. It is also because of the economic importance conferred on this portion of the Earth's crust by the hydrocarbon, uranium and other metallic and non-metallic ore resources contained in its sedimentary and eruptive units.

La Reunion is an oceanic intra-plate volcanic island located at the southern-most part 0 of the Mascarene Basin at 21 0 07' S, 55 32' E (Figure 1). It lies south of the Mascarene Plateau and Mauritius Island but is a distinct topographic feature on the rather flat ocean bottom of the Mascarene Basin, whose age is paleocene in the vicinity of the island (Schlich, 1982), and whose lowest point is more than 4000m deep. La Reunion is ellip- tical in shape (50 X 70 km) with a NW-SE elongation. It is composed of two volcanoes: Piton des Neiges and Piton de la Fournaise. A third volcanic structure has been recent- ly discovered on the east submarine flank of the island (Unat et aI. , submitted). Piton des Neiges, a dormant and deeply eroded volcano, rises to a height of 3069 m and oc- cupies the northwestern two-thirds of the island. Piton de la Fournaise (2630 m), one of the most active basaltic volcanoes in the world, began to grow more than 3. 5 X 1O~ years ago on the southeast flank of Piton des Neiges. The evolution of Piton de la Fournaise (Chevallier and Bachclery, 1981) is marked by the formation of three sub-concentric nested calderas (Figure 2).The boundaries of the two older calderas are more or less buried or eroded.