570 MESSES. JTTKES-BEOWKE AND W. HILL ON THE LOWEE PAET 



of the wide transverse valley lying between Hillingdon and West 

 Newton, at which place there are two good sections in the Grey 

 Chalk, though they show nothing worthy of note. 



A few feet of the base of the Grey Chalk may be seen overlying 

 the Totternhoe Stone at Sandringham and Dersingham. A large 

 pit in the central part of it occurs at Ingoldsthorpe, and its base is 

 again seen in the pit at Snettisham. 



Hard, yellowish, nodular chalk, but little above the Eock, is seen 

 less than a quarter of a mile north of the church of Sherborne, in 

 a small exposure by the roadside and just by an old quarry, the 

 sides of which are now overgrown and its floor cultivated. Dr. 

 Barrois says that in this quarry he could recognize the hard nodular 

 bed (i. e. the Melbourn Eock) which throughout England occurs at 

 the base of his zone of Inoceramus lahiatus. His list of fossils gives 

 those most common at this horizon. 



The Melbourn Eock is well exposed in the upper part of the 

 large quarry at Heacham. It is seen here as a very hard, yellowish, 

 nodular rock, with rough fracture, massively bedded, and about 

 six feet thick, ffliynclionella Guvieri, Echinoconus subrotundus, and 

 E. castanea, with Inoceramus mytiloides, occur. 



It is much weathered, and splits along greenish marly veins in 

 thin platy pieces, with a very rough, nodular, and uneven surface. 

 The base is clearly marked, but it rests directly on hard white chalk 

 without the intervention of a marl-band ; there is, however, a thin 

 layer of buff-coloured marl in the white chalk, about one foot below 

 the base of the Melbourn Eock, and a second is seen near the top 

 of the lower pit. These bands are similar to those at Hillingdon, 

 where they probably occupy the same position with regard to the 

 Eock as they are seen to do in this case. 



The Lower Chalk weathers into thin platy pieces, with a more 

 even surface and fracture, which contrasts with the rough nodular 

 surface of the Melbourn Eock. 



The entire section of both upper and lower pit is as follows : — 



Melbourn 

 Eock. 



Grey 

 Chalk. 



Upper Pit. feet, 

 Rough, thin-bedded chalk and soil 3 



\ Hard, yellowish, nodular rock, massively bedded 6 



/Thin-bedded, hard, rather rough, whitish chalk in two 

 courses, separated by a thin, buff-coloured, marly band . 2 

 Thin-bedded, hard, whitish chalk ; base obscured by talus 3-4 



Lower Pit. 



Thin-bedded, platy chalk, becoming more massively bedded 

 in its lower part, but not equally so ; a marly band near 



the top 30 



Totternhoe I Eather dark-grey gritty chalk, with green-coated nodules 



Stone. \ at its base 2 



Chalk-marl. Hard creamy-white chalk-marl seen for 12 



It will be seen, therefore, from the section given above of both 

 the upper and lower parts of Heacham quarries, that, with the 

 exception of two or three feet of Chalk-marl, the whole of the 



