January 22, 1897.] 



SCIENCE. 



149 



mental methods are perfect, or that well con- 

 sidered changes may not in some cases be 

 wholly desirable. All I desire to do is to point 

 out that the nostrum now offered is by no 

 means a cure-all, and that the attainment of 

 ideal conditions depends almost wholly on an 

 honest recognition by the whole country, as 

 represented by Congress and the executive, of 

 merit, fitness and resulting permanency of ten- 

 ure in the staff of the scientific bureaus. 



Washingtonian. 

 Washington, January 16, 1897. 



THE .JURASSIC WEALDEN (TITHONIAN) OF ENG- 

 LAND. 



Pkof. O. C. Marsh has called again atten- 

 tion to the Wealden formation of England — an 

 abnormal deposit, rather puzzling. Every ob- 

 server working at geographical geology and 

 general classification has been struck by an 

 enigma in the otherwise classical classification 

 of the strata of England. Between the Port- 

 land stone at the island of Portland and at 

 Durstoue bay, and the Lower Greensand of 

 the Middle Cretaceous, we have a series of 

 beds, mainly sands and clays, with some lime- 

 stone and dirt in the inferior part, which has 

 been called a fluvio-marine and fresh-water 

 formation, of a thickness of about 1,-500 or 2,000 

 feet, designated generally by the name of Weal- 

 den. The name of ' Weald formation, or 

 Wealden,' was first introduced in the English 

 classification by P. I. Martin in 1828 {A Geolog- 

 ical Memoir on. a Pari of Western Sussex, p. 40, 

 4to, London). 



Dr. William PI. Fitton accepted it, and in his 

 celebrated memoir. Observations on some of the 

 strata between the Chalk and the Oxford oolite in 

 the Southeast of England, Trans. Geol. Soc. Lon- 

 don, second series. Vol. IV., p. 103, London, 

 1836, gives a detailed account, dividing the 

 Wealden into three great groups, called the 

 Purbeck strata, Hastings sand and Weald clay 

 proper. 



Dr. Gideon A. Mantell is generally credited 

 as the author of the stratigraphic position in 

 English classification of the Wealden formation 

 {Illmtrations of the Geology of Sussex, 4to, Lon- 

 don, 1827, and A sketch of the Geological structure 

 of the Southeastern jiart of Sussex, Lewes, 1818). 



He puts it as the lowest part of the Cretaceous 

 formation. 



The classification of Mantell was generally 

 accepted until November, 1849, when Edward 

 Forbes observed at Portland and Swauage that 

 Fitton and Mantell made mistakes, especially 

 in regard to the Purbeck marble series, and, 

 after some close and excellent observations, 

 recognized that the Purbeck was Jurassic and 

 not Cretaceous. As he humorously says in a 

 letter to Eamsay : " The ' geology of Eiigland ' 

 may be ' done ' by the old fellows, but it is not 

 overdone yet." {Memoirs of Edward Forbes, y>. 

 461, London, 1861.) Edward Forbes was the 

 man to correct errors of classification in regard 

 to the Mesozoic and Tertiary. He has no 

 equal for sharp observations and correct con- 

 clusions. Unhappily he was not able to finish his 

 work ; his premature death in 1854 arrested 

 completely the researches he inaugurated so 

 well in Dorset and the Isle of Wight. Even 

 his work, as he has entitled it, ' A Description 

 of the Purbeck and Wealden fresh-water and 

 fluvio-marine strata of Dorsetshire and the Isle 

 of Wight, with comparative remarks on syn- 

 chronous strata elsewhere' (Preface, p. vii., 

 On the Tertiary fluvio-marine formation of the Isle 

 of Wight, London, 1856), was never published ; 

 only a short notice was given to the public in 

 the British Association Report for 1850, under 

 the title ' On the succession of organic remains 

 in the Dorsetshire Purbecks. ' However, short 

 as it is, the notice of Forbes brought the age of 

 the Wealden once more before the English 

 geologists, and one of them who knew best the 

 Secondary or Mesozoic formations, the nephew 

 of the celebrated 'Strata Smith,' Prof. John 

 Phillips, of the University of Oxford, in his re- 

 markable Manual of Geology,* pp. 282-318, 



* Extract from a letter of Prof. John Phillips to 

 Jules Maroon. * * * "As to the propriety of 

 placing the Wealden in the Cretaceous I have my 

 doubts. Certainly the fresh-water fossil remains, 

 which otherwise are not characteristic of the age of 

 strata, are not in favor of uniting the upper part of 

 the Wealden with the Cretaceous, while the Mcgalo- 

 saurus and other Saurians, as well as the fishes and 

 plants found in the Middle (Hastings Sands), protest 

 loudly against the separation of the Wealden from 

 the Oolites." John Phillips. 



St. Mary's Lodge, Yore, July 23, 1887. 



