Grenada’s landform structure is characterized by a steep rugged interior and a relatively low rolling coastal periphery. The interior is dominated by steep mountain peaks, sharp ridges and deep narrow valleys flowing towards the coastline. These interior formations are due to volcanic activity leaving mountain tops of andesite and basalt lavas.
The coastal periphery is generally gently sloping and consists of weathered volcanic rocks and mudslide deposits. The coastal areas on the west are steeper than that on the east coast. Grenada was formed by a series of volcanic eruptions during the Tertiary and Pleistocene periods (Ternan et al, 1989). Details of the island’s geological structure are indicated in Figure 1. In some areas, sedimentary rocks of Tertiary and Quaternary period are also present.
The islands of Carriacou and Petit Martinique are also of volcanic origin. About two thirds of Carriacou is volcanic with the other one third consisting of fossiliferous limestone. (Jessemy 1999).
Vernon et al (1959) suggests that climate is a major factor influencing the distribution and location of soils in Grenada. In the interior where the rainfall is higher, there is a high degree of chemical weathering resulting in highly leached clay. Given the predominance of iron and aluminum oxides, soils in the high interior are reddish. They tend to have a poor nutrient storage capacity and are fragile. Most of the soils in Grenada are classified as clay loams. In fact, clay loams account for 84.5% with clays 11.6% and sandy loams 2.9%. Figure 3 indicates the main types of soils and their location.
The Belmont Clay Loam dominates the north of the Island. The central part of the island is dominated by Capitol and Belmont Clay Loam and the south is dominated by Capitol Clay Loam. Woburn Clay Loam occurs along the coastal areas to the south and west of Grenada. Clay soils are found along the coast of the Island (Jessemy 1999).