194 Mr. S. V. Wood on the Red Crag 



with those traces, however, is preserved more perfectly a band 

 of phosphatic nodules that I felt no hesitation in identifying 

 with the basement band of the fifth-stage Red Crag. I enter- 

 tain no doubt that this trace of Crag does not belong to any of 

 the beach stages ; and the only question that presents itself to 

 me is whether it may be a remnant of the base of the Fluvio- 

 marine Crag : that Crag, being water-deposited, may, like the 

 Coralline, have in places under it these nodules. The means of 

 ascertaining to which of these two this trace of Crag belongs 

 could only be aflForded by an excavation in the Aldbro' 

 brick-field. In colour the Thorpe beds do not at all resemble 

 this trace of Crag, which is ferruginous ; and the impression 

 I entertain is strong that the two are distinct. There can be 

 little doubt that this Crag with the nodule-band underlies the 

 clays forming the brick-field higher up the rise ; and in that 

 respect their relative positions agree with those we find on the 

 opposite side of the Coralline-Crag ridge, where fifth-stage Crag 

 passes at Chillesford up into these beds without interruption. 



The conclusion that I have formed from these observations is 

 that the Fluvio-marine Crag of Thorpe is inferior to the fifth- 

 stage Red Crag, and as old therefore, at least, as the uppermost 

 beach stage. It must be admitted that the evidence for such a 

 conclusion is very incomplete and unsatisfactory ; but the general 

 consideration of the geographical conditions of the period furnish, 

 to my mind, a support to the inference I have drawn. There 

 can be little doubt that the fifth-stage Crag was introduced by a 

 slight depression. That depression would enable it to cover, 

 although very thinly and feebly, portions of the Coralline Crag 

 never covered by the beach stages. Since this faint trace of 

 Crag at Aldbro' immediately underlies the laminated clays, it 

 must (if not the Fluvio-marine itself) be newer than the Fluvio- 

 marine Crag; or else the latter is newer than the laminated clays, 

 in which case we ought to find it overlying the clays ; but such 

 is not the case — the clays passing, without a break, up into the 

 sands of the Drift. If, on the other hand, it be identical with 

 the trace of Crag at Aldbro* underlying the clays, it must 

 be at least as old as the fifth-stage Crag, that underlies and 

 passes up into those clays. I can therefore come to no other 

 conclusion than that the Fluvio-marine Crag is as old as the Red 

 Crag, and most probably older than that part of it represented 

 by the fifth-stage or water- deposited Crag. 



The descriptions with which we have been furnished by 

 Messrs. Woodward and Gunn, and by Sir Charles Lyell, of the 

 beds occurring along the coast northwards from Southwold, have 

 not been of such nature as to afford any satisfactory comparison 

 with the formations I have been discussing. Nothing less than 



