104 Frof. E. Hull — The Great Pleistocene Lake of Portugal. 



of these formations, when we remember the patient search that has 

 been necessary in Europe in order to obtain fossil evidence for the 

 age of important formations. Kogers ^ instances the work done in 

 the north of Devonshire by two generations of geologists before the 

 Morte slates were found to be fossiliferous. We may still hope that 

 some of our more promising shales and limestones will yet yield 

 palseontological evidence which will enable them to be correlated 

 with the classic systems of Europe. 



{To he concluded in our next number.) 



11. — The Physical History of the Great Pleistocene Lake 



OF Portugal.^ 



By Professor Edward Hull, LL.D., F.R.S., F.G.S. 



AEECENT visit to Portugal has given me an opportunity of seeing 

 the geological features of the neighbourhood of Lisbon and 

 the Lower Tagus ; and though of a somewhat cursory nature I venture 

 to bring them before the Society, being supplemented by reference 

 to the investigations of previous observers, and a study of the 

 excellent geological maps which are in the library of this Society. 

 I make no pretension to be an original explorer, but I hope to be able 

 to show that there is a very interesting physical history, not hitherto 

 written so far as I am able to discover, bringing down the account of 

 the changes which have taken place from the Cretaceous period to the 

 Eecent, or Quaternary, epoch. 



In addition to my own observations I have relied for the necessary 

 data for this paper on the geological maps of Portugal,^ together 

 with the papers of the late Mr. Daniel Sharpe * and of Mr. Smith * 

 of Jordan Hill, which sufficiently put us in possession of the 

 materials for an historical sketch of the remarkable physical changes 

 which the Iberian Peninsula has undergone, at least along its 

 western margin, in Tertiary and still more recent times. 



Geological Formations. 



The formations bordering the lower banks of the Tagus near 

 Lisbon are arranged by Sharpe in the following order of succession : — 



Mr. D. Sharpens Classification. 



1. Upper Tertiary Sands, etc. 



2. Alraada Beds (Marine). 



3. Lower Tertiary Conglomerate. 



4. Hippurite Limestone (Cretaceous). 



1 "Geology of Cape Colony," p. 114; Loudon, 1905. 



* Read before the Geological Society, December 6th, 1905. 



* "Carta Geologica de Portugal,"' ed. by Carlos Riberio & J. F. N. Delgado 

 (1876) ; "Mapa Geologico de Espana y Portugal," by D. F. de Botella (1879). 



* " On the Geology of Lisbon " : Trans. Geol. Soc, ser. ii (1839), and Q.J.G.S., 

 vol. vi, p. 134 (1850). 



5 " On the Age of the Tertiary Beds of the Tagus " : Q. J.G.S., vol. iii, p. 410 

 (1847). 



