133 



stated that the spinal marrow offers, at the period of development in 

 question, several other peculiarities, some of them bearing likewise 

 a segmental character ; but he reserved a detailed description of 

 them for a future communication. 



February 27, 1854. 



A paper was read by Professor Challis, entitled " A direct Method 

 of obtaining by Analysis the mean motions of the apse and node of 

 the Moon's Orbit." See Philosophical Magazine, vol. vii. p. 278. 



Also a paper by Mr. J. B. Phear on some parts of the Geology 

 of Suffolk, particularly with reference to the Valley of the Gipping. 



The deposits which constitute what is often termed the glacial 

 formation, but which the present state of our knowledge hardly 

 allows us to designate by a name significant of a common origin, 

 present so much confusion to the inquirer, and impose upon him so 

 much laborious research by the extent and the unconnected character 

 of their distribution, that they have hitherto met with less attention 

 than their importance deserves. 



The county of Suffolk seems to be a district where a portion of 

 these deposits is manifested with more than usual distinctness, and 

 is capable of being studied with comparative facility. The county 

 is separated from Norfolk on the north by the well-marked valleys of 

 the Ouse and the Waveney, is bounded on the east and south by the 

 sea and valley of the Stour, and is bordered by chalk uplands on the 

 north-west ; the whole central portion is thickly covered with a mass 

 of blue drift-clay, cut into abrupt undulations by a network of val- 

 leys. This clay is totally without any symptom of stratification, and 

 is full of fragments of all rocks of the secondary period, including 

 specimens of granite and other igneous rocks. 



Wells sunk in different parts of the county show this drift- clay to 

 have a thickness varying from 200 feet to a few inches ; it seems to 

 thin off from the northern and western parts of the county towards 

 the coast, and only exists in the shape of outliers beyond a line 

 passing through Sudbury, Hadleigh, Bramford, Woodbridge, and 

 Saxumndham ; a line, it may be remarked, nearly coinciding with 

 the edge both of the London clay and of the crag, and approximately 

 passing through the heads of the tidal estuaries of the Orwell, Deben, 

 Ore and Aide. The clay is almost universally underlaid by an un- 

 fossiliferous sand ; and there is reason to conjecture that this sand, 

 of a prevailing red colour, passes out beyond the just-mentioned line, 

 and covers in many places the surface of the strip of land between 

 it and the sea. 



A detailed examination of the Gipping valley reveals a well- 

 marked and connected line of sand cliffs fringing it, and its Codden- 

 ham tributary in particular, at a high level on both sides ; the sand 

 is generally pure white, though often red, horizontally stratified and 



