284 Reports and Proceedings — 



The authors give an account of previous geological work relating 

 to Dundry Hill, especially that which refers to the correlation of its 

 strata. Then they describe the different exposures on the Hill, 

 together with the results of various excavations carried out by 

 quarrymen under their superintendence for the purpose of the 

 present communication. Besides demonstrating the secpience of 

 the strata of Dundry Hill, the authors are able to show as special 

 results — 



The rapid easterly attenuation of the Freestone. 



That there is a non-sequence in the Dundry deposits. 



That the chief fossiliferous bed — the Ironshot Oolite — extends 



over a very small area. 

 That the absence of this bed is due to removal by almost contem- 

 poraneous denudation. 

 That in the easternmost portion of the Hill this bed and all the 

 other beds of what is called Inferior Oolite have been removed 

 by this denudation, so that only a thin cap of what would be 

 called " upper beds of Inferior Oolite " rests on a thick clay- bed 

 of the age of the Midford Sands. 

 That deposits contemporaneous with what are called "Upper 

 Lias" and "Midford Sands" in other places are found in some 

 thickness at Dundry Hill, attaining as much as 65 feet. 

 That the Lias Marlstone-rock is present at Dundry Hill and 

 outcrops in many places on its flanks, but that this rock-bed is 

 also wanting from many parts of the Hill. 

 That the Geological Survey have presumably mistaken this 

 Marlstone-rock (which is an Ironshot stone) for the Ironshot 

 Oolite — the chief fossiliferous bed of the Dundry Inferior 

 Oolite, and formerly called Humphriesianum - zone — beds 

 nearly 100 feet apart. 

 That, as a consequence, the map of the Geological Survey shows 

 round the greater portion of the Hill the boundary-line of the 

 base of the Inferior Oolite drawn as much below the Marlstone 

 as would be correct if this rock had actually been the well- 

 known Ironshot Oolite. 

 That, as a further consequence of this, the map of the Geological 

 Survey shows coloured as Inferior Oolite, strata which would be 

 mapped as Lower Lias, Middle Lias, Upper Lias, and Midford 

 Sands in other localities, and that in places the limit for 

 Inferior Oolite, according to the Survey, is as much as 600 yards 

 beyond that of the authors. 

 The authors append a map of the strata of Dundry Hill, coloured 

 on a palaeontological basis, and they show how it may be compared 

 with the map of the Survey and with a map by Saunders. 



3. " On the Geographical Evolution of Jamaica." By J. W. 

 Spencer, M.A., Ph.D., F.G.S. 



The object of the paper is to set forth the physical and geological 

 characteristics of Jamaica which bear upon the problem of its late 

 high elevation and former connection with the continent, and to 



