Introduction
The older rocks in Jamaica are exposed in the 'Cretaceous inliers' (Shown below). An inlier is an area of older rocks surrounded by an area of younger rocks (an outlier is the opposite - an area of youmger rocks surrounded by older rocks). The map below shows some of the more imporatnt 'Cretaceous' inliers in Jamaica. However, in some places Paleocene rocks are also included (e.g., in the Central Inlier), because sedimentation was continuous across the Cretaceous (Maastrchtian)-Paleocene boundary.
A simplified map showing the distribution of the main Cretaceous Inliers in Jamaica.
The Cretaceous inliers of Jamaica can be grouped into broadly geographical units:
(a) The Blue Mountains Inlier and inliers along the north-eastern margin of the Wag Water Belt (e.g. Sunning Hill and St Peter's inliers);
(b) The Benbow Inlier (including the Mount Diablo Inlier);
(c) The Above Rocks Inlier and inliers along the south-western margin of the Wag Water Belt (e.g., Jacks Hill and Lidos Gap inliers);
(d) Lazaretto Inlier;
(e) Central Inlier and associated inliers (Spring Vale, Pedro River, Banana Ground and Nottingham inliers);
(f) St Ann's Great River Inlier;
(g) The St James (Sunderland, Carlton Hill, Maldon, etc.) inliers;.
(h) The 'Hanover Block' (Lucea, Green Island, Grange, Jerusalem Mountain) inliers.