TRANSACTIONS OF THE GEOLOGICAL SOCIETY OF LONDON. SECOND SERIES. VOLUME II. PART THE SECOND. Quod si cui mortaliura cordi et curae sit, non tantum inventis haerere, atque iis uti, sed ad ulteriora penetrare; atque non disputando adversarium, sed opere naturam vincere ; deni- que non belle et probabiliter opinari, sed certo et ostensive scire ; tales, tanquam veri scien- tiarum filii, nobis (si videbitur) se adjungant. Novum Organum, Prwfatio. LONDON: PRINTED BY RICHARD TAYLOR, SHOE LANE. SOLD AT THE HOUSE OF THE GEOLOGICAL SOCIETY, No. 20, BEDFORD STREET, COVENT GARDEN. 1827, OFFICERS AND COUNCIL OF THE GEOLOGICAL SOCIETY OF LONDON. 1827- PRESIDENT. WILLIAM HENRY FITTON, M.D. F.R.S. VICE-PRESIDENTS. ARTHUR AIKIN, Esq. F.L.S. Rev. WILLIAM DANIEL CONYBEARE, F.R.S. JOHN BOSTOCK, M.D. F.R.S. L.S. & H.S. Rev. ADAM SEDGWICK, F.R.S. Woodwardian Professor, Cambridge. SECRETARIES. WILLIAM JOHN BRODERIP, Esq.F.L.&H.S. | RODERICK IMPEY MURCHISON, Esq. F.R.S. FOREIGN SECRETARY. HENRY HEULAND, Esq. TREASURER. JOHN TAYLOR, Esq. F.R.S. COUNCIL. HENRY THOMAS DE LA BECHE, Esq. F.R.S. WILLIAM HASLEDINE PEPYS, Esq. F.R.S. J. E. BICHENO, Esq. Sec. L.S. L.S.& H.S. DAVIES GILBERT, Esq. M.P. V.P.R.S. Rev. JOHN HONEYWOOD RANDOLPH. GEORGE BELLAS GREENOUGH, Esq. F.R.S. CHARLES STOKES, Esq. F.R.S. S.A. & L.S. JOHN FREDERICK WILLIAM HERSCHEL, J. F. VANDERCOM, Esq. Esq. Sec R. S. HENRY WARBURTON, Esq. M.P. F.R.S. ARM AND LEVY, Esq. THOMAS WEBSTER, Esq. CHARLES LYELL, Esq. F.R.S. & L.S. THOMAS YOUNG, Esq. ADVERTISEMENT. THE Editors of the Transactions of the Geological Society are directed to make it known to the Public, that the Authors alone are respon­ sible for the facts and opinions contained in their respective papers. It is requested that all letters and communications to the Secretaries, and presents to the Society, may be addressed to the House of the Geological Society, No. 20, Bedford Street, Covent Garden, London. .