HARDWICKE'S SCIENCE-GOSSIP. 



271 



THE STORY OF THE "CRAGS." 

 By J. E. Taylor, E.G.S., &c. 



IT may be that some of the friends who are good 

 enough to listen to what we have to say, do 

 not understand what is meant by the term " Crag." 

 Some of our fellow story-tellers have already re- 

 marked that many of the terms used in geology 

 have been borrowed from vulgar use. and elevated 

 into scientific expressions. It is necessary to under- 

 stand the latter before much progress can be made. 

 This, however, is not the place for explaining any 

 other than our own. "Crag," then, is a word 

 common in the Eastern counties, especially in 

 Norfolk and Suffolk, and is applied to those thick 

 beds of marine shells whose history we purpose 

 relating. Ask any person living near the localities 

 where these strata crop out, and they tell you, in a 

 dialect you will find it difficult to understand, to 

 what the word is applied. 



Geologically, the "Crag" beds belong to that 

 period of time known as the Pliocene. They are 

 deeply interesting, on account of their connecting 

 the past with the present. They also give you a 

 good idea of the physical and climatal conditions of 

 this country just before the extreme and lasting 

 cold of the Glacial epoch set in, and testify to 

 general circumstances not greatly unlike those 

 which now prevail in these latitudes. We " Crags " 

 are three in number, of which the oldest is that 

 known as the Coralline. Then comes the Red, and 

 lastly, the Norwich. The former goes also by the 

 name of Older Pliocene. 



We must take you back to a period— that of our 

 birth — when the climate was rather warmer and 

 milder than it now 'is. A good portion of Suffolk 

 was then lying under a tolerably deep sea, along 

 whose floor beds of shells were forming. The 

 genial temperature of the water was favourable to 

 the development of animal life. Hosts of beautiful 

 echinites {Temnechinus) slowly pulled themselves 

 over the smooth bottom. These creatures subse- 

 quently became extinct in English areas, and 

 naturalists believed they had passed out of exist- 

 ence altogether. We hear, however, they have 

 been met with quite recently whilst dredging in 

 deepish water off the coasts of Florida, on the 

 other side the Atlantic. You may guess, therefore, 

 the time which has passed away since the Coral- 

 line Crag was formed, by the agencies which have 

 slowly driven a once English inhabitant to take up 

 its isolated abode in American waters. The mol- 

 lusca literally swarmed over the Suffolk area, and 

 it is out of their broken and disunited shells that 

 we " Crag" beds have been formed. Chief among 

 the generic forms were the Astartes, whose specific 

 abundance was only excelled by their individual 

 powers of multiplication. Next came the Pectun- 



culus, whose members literally swarmed. The Cy- 

 prina was not absent, and its beautiful valves arc 

 among the chief spoils to be obtained at Orford, 

 in Suffolk. One genus, Cardita, is also largely 

 represented, and you may frequently disinter it 

 with both valves still united. No fewer than three 

 hundred and fifty species of mollusca lived in the 

 waters of the Coralline Crag sea; and in the beau- 

 tiful cream-coloured deposits you may pick these 

 out with as much ease as you would the empty 

 valves on some sea-beach. To those who are fond of 

 conchology, and who love still more to read off the 

 simple but profound lessons which fossil shells 

 teach, we would recommend a visit to those parts 

 of Suffolk where we lie in original repose. It is 

 like walking over the dried-up bed of a recently- 

 existing sea, and obtaining those secrets which the 

 dredge and other instruments can so imperfectly 

 explain in these days. Besides the great number 

 of species of mollusca found here, and in addition 

 to the Echinodermata, or " sea-urchins," there are 

 no fewer than one hundred and thirty species of 

 Bri/ozoa, or "sea-mats," which have been disco- 

 vered. Some of them, such as Fascicularia, are 

 quite unlike anything now existing, although they 

 lived in what were then British waters, at a period 

 geologically so recent. Corals, all of them belong- 

 ing to the solitary kinds, are also plentiful, and 

 their beautiful shapes are only excelled by the 

 ornate sculpturing of the " sea-urchins." Alto- 

 gether, therefore, you may form some idea of the 

 rich treat for the naturalist which is to be obtained 

 simply by " collecting " in our beds ; whilst, if your 

 philosophy goes deeper, you will not be long before 

 you come to some such conclusions as the following, 

 all of which form a veritable portion of our life- 

 history. 



The sea of the Coralline Crag was subject to 

 occasional extremes. On its floor were met species 

 of shell-fish which are now regarded as indicating 

 wide differences of climature. The Astartes de- 

 cidedly point to northern conditions; but such 

 forms as Pyrula, Volida, and Cassidaria, as dis- 

 tinctly point to warm waters. We can hardly speak 

 positively on this point, but we think these extremes 

 may have been produced by alternate currents of 

 warm and cold water, which, as we have heard, are 

 found to exist in the deeper parts of temperate seas 

 at the present time. Whether or not, it is certain 

 that such circumstances would only make the life- 

 forms more various and the species more abundant. 

 The total number of shells which you may call 

 " southern," met with in this the oldest Crag, is 

 twenty-eight— not a large number, you will say, out 

 of the total. But, small as this number is, it will 

 assist us in explaining to you the gradual change 

 of the physical conditions which occurred during 

 the Pliocene epoch. Some of them were driven 

 away from these latitudes by the encroaching cold, 



