254 Tristram— Valley of the Jordan. 
Red Sandstone series. Such concession would not mean that their 
‘ date of deposition, with reference to the burial of the Stagonolepis 
in the siliceous and aluminous muds of the estuary, was exactly 
coeval with the time when some few representatives of the Pterich- 
thys family found their way down south, and lived in the shallow 
waters which washed the shores of certain islands, now known to 
us, geographically, as parts of England and Wales; to wit, Shropshire, 
Herefordshire, and Monmouthshire ; for it is very doubtful whether 
any scheme exhibiting the contemporaneity of one deposit with 
another in time can be drawn. Indeed, it must be borne in mind that 
any one period in geological time studied for any scientific purpose 
must necessarily be regarded as a geographical study, and that the 
landscape which the mind of the student draws out of the materials 
at his disposal is one very liable to error ; for, when stretched before 
his mental vision, it has to be tested by geographical conditions now 
existing on the surface, and not by any presumed state of affairs 
common to the whole physical and paleontological economy of the 
world. Dame Nature shifts the scenes in a very complex and 
elaborate manner, and ‘rings in the next piece’ with a complete 
knowledge of the varied and numberless interests involved in its 
construction. 
LV. On THE GroLocy AND PHysicAL FEATURES OF THE VALLEY OF 
THE JORDAN, THE DbAD SEA, AND THE ADJACENT DISTRICTS. 
By the Rey. H. B. Tristram, M.A., F.L.S. 
[Abstract of Paper read before the British Association, September 1865.] 
ANY travellers have spoken of the numerous traces of vol- 
canic action to be found in the neighbourhood of the Dead 
Sea; but the author states that he invariably found the ‘lava- 
currents’ of M. de Sauley to be nothing more than deposits of 
silica and nodules of oxide of iron, while his ‘ extinct craters’ proved 
to be the flat summits of limestone-hills. 
The two parallel ranges of hills which run nearly north and 
south, and form the eastern and western margins of the valley which 
includes the Ghor and the Dead Sea, and extends nearly to Akabah, 
consists chiefly of rocks apparently of the ege of the Lower Chalk, 
and having a synclinal dip. Round the shores of the Dead Sea, 
there are abundant traces of a much more recent deposit, probably 
Post-tertiary; it is a saliferous marl, containing unfossilized Shells 
of the species that now exist in the Jordan. 
Descending from Jericho to the Dead Sea (a fall of 600 feet), a 
good notion of the physical features of the country may be obtained. 
First, there is an old terrace-line, about 400 feet above the present 
level of the Jordan, formed of a very coarse and soft limestone; 
then the lower terrace-line, 55 feet above the present level of the 
plain, composed of friable earths strongly impregnated with various 
salts, and having a slight but hard saline crust at the top, besides 
many interstratified layers. This second ‘terrace is scarped and 
furrowed in all directions by aqueous action, and where the plateau 
projects into the plain it forms the tops of a series of mamelons, 
