102 Mr. II. Seeley on Cambridge Geology : — 



vening spaces occurred, in which it was so soft that " one could 

 put his arm in and move it about/' — a circumstance probably 

 indicating a water-bearing stratum at no great depth beneath. 



The question here arises, Is this calcareous band identical 

 with that of St. Ives, above which it would seem to be at least 

 30 feet ? If this is assumed, it is clear that as the Elsworth 

 rock dips south, it cannot be identical with the stratum at St. 

 Ives, which also would dip south, and therefore be at a very 

 great depth beneath it. Another conclusion from this assump- 

 tion would be, that the fossils in the clay at Bluntisham should 

 be identical with those of the clay above the rock near St. Ives ; 

 while we should expect a considerable difference between the 

 fossils of the St. Ives limestone and that of Elsworth. But 

 neither of these conditions is met with. 



Although the clay at Bluntisham is capped with boulder clay, 

 and the fossils of both, which were collected for me, are mixed 

 together, and are therefore to be appealed to with great caution, 

 I think it can yet be said with confidence that they indicate a 

 zone above that of St. Ives ; while, after some hours' work in the 

 St. Ives rock, I only obtained, in nineteen, three species not pre- 

 viously met with at Elsworth. This must be conclusive that the 

 Bluntisham rock is superior to that of St. Ives, while it strongly 

 suggests that the latter is not far removed from the zone of the 

 Elsworth limestone. The few fossils from the clay above the 

 rock at the latter place are such that there can be no doubt that 

 the rock beneath is not inferior to that of St. Ives : it may be su- 

 perior or on the same parallel ; while the alternatives with respect 

 to the Bluntisham bed are that it should either be continuous 

 with or inferior to it. Thus, then, we shall have the point of up- 

 heaving force greatest either between Elsworth and St. Ives, or 

 at some unknown place further north. If the latter condition 

 obtained, the St. Ives rock would be inclined to the horizon; and 

 as the bed at Bluntisham is in elevation apparently only 30 feet 

 above it, it would, even if the angle of inclination were less than 

 that of the Elsworth bed would lead us to expect, become, when 

 it reached Bluntisham, either coincident with the deposit there 

 or many feet above it. Moreover, the Elsworth rock would be 

 100 feet above that of St. Ives. The fossils, however, as has 

 already been seen, indicate conclusions very different; and so the 

 supposition may safely be dismissed. The point of least resist- 

 ance in the upheaval, then, was between Elsworth and St. Ives ; 

 and therefore the rock, which rises to the surface at Elsworth, 

 must dip down again somewhere to the north in the St. Ives 

 neighbourhood. Hence the question stands thus : Is the Blun- 

 tisham rock (or are both it and the St. Ives beds) a continuation 

 of those at Elsworth ? If the supposition be adopted that the 



