NOTES AND QUERIES. 



n 



NOTES AND QUERIES. 



The "Crackers" and other Fossiliferous Nodules. — "Sir, — I have 

 perused the works of Mantell, Lyell, Ansted, and other standard authors on Geo- 

 logy, besides having regular access, through a friend, to the Quarterly Journal of 

 the Geological Society and to other miscellaneous works on the science ; but 

 amongst them all I have not as yet been able to obtain the slightest clue that 

 would tend to solve the undermentioned geological phenomena ; and, thinking 

 that either yourself or some of your numerous readers could throw some light upon 

 the subject, I take the liberty of asking space for that purpose in your really 

 popular, and, on that account, valuable periodical. 



" It is a fact patent to all geologists who have visited the Isle of Wight, that its 

 cliffs on the southern coast exhibit some good sections of the Lower Greensand, 

 probably the best in the kingdom, more especially those between Rocken End and 

 Atherfield Point, where this series may be studied throughout its entire thickness 

 from the Gault to the Wealden beds. 



" It is not, however, to the strata themselves that my remarks apply, but to 

 the condition in which some of the organic remains are found in the lowermost 

 portion termed the ' Crackers Rocks.' 



" In examining the excellent chart by Dr. Hilton, it will be seen that the 

 * Crackers' are composed of two layers of large nodules, one above the other, and 

 about ten or eleven feet apart, embedded in a loose red sand. The uppermost are 

 but little sought after by the experienced geologist, as they are very hard and 

 tough, and the fossils they contain are very difficult to be separated from the 

 matrix ; but the lower portion contains those splendid fossils which are world- 

 famous. The best place for the collector to search for the ' Cracker' fossils is to 

 begin a short distance to the eastward of the road made by the coastguard in the 

 .cliff, and then to travel westward as far as another path up the cliff, made by the 

 fishermen, where the ' Cracker-rock' runs out, and the next bed in the succession, 

 the lower ' lobster-bed,' appears. 



" After a founder of the cliff, large nodules may be found with sometimes a few 

 fossils on their outsides ; and these, when broken, sometimes disclose whole colo- 

 nies of Gervillia ancejjs, with now and then Trigonia dcedalea and an ammonite or 

 two on the outside. The nodule itself is composed of a hard, compact, grey or 

 bluish rock, enclosing other nodules or smooth sandy concretions, of a lightish- 

 brown colour. These can be easily extracted, and will be found to contain myriads 

 of small fossils, such as Venus, Thetis, Rostellaria, Natica, Pteroceras, Ammonites, 

 Crustacea, and numerous others, nearly all perfect. Hence I infer that, like those 

 of the lias, they all met their death in a sudden manner. 



"Now the question to be solved is — How came these animals, of different 

 genera and species, and consequently of dissimilar habits, so attracted together as 

 to die and become entombed in one common grave ? Were they all or any of 

 them carrion-eaters ; and, if so, were they attracted together by abundance of food 

 through the destruction of any one species of animal, or by mere chance i Or did 

 such nodules once form part of the floor of a sea-bottom, that, being broken up, 

 yielded these concretions to be washed into the strata where they now abound, 

 and where, becoming thus embedded, the outer coating has subsequently formed 

 around them ? If this be the case, where are the equivalents now of such concre- 

 tions ? Besides, the cliff is chiefly composed of sand. 



* A local name, given them by the fishermen on'account of the sea having excavated a sort of 

 cavern in the cliffs, into -which the waves enter, carrying with them a portion of air, which causes 

 a concussion; hence the term, " Crackers Rocks." 



