42 



may commence long before that of the other salts brought down in 

 solution at the same time. 



In the Penrith Sandstone we seem to have had large quantities 

 of carbonate of iron and carbonate of magnesia deposited first. If 

 there were any other minerals they have gone and left no traces 

 behind. By the time the top beds of the Penrith Sandstone were 

 being spread out, a little Common Salt had begun to be thrown 

 down; but just at this period there seems to have been a temporary 

 change of physical conditions, for we get a change of sediment 

 and rocks of another kind. After this temporary change we had 

 carbonate of iron as before, this time accompanied by sulphate of 

 lime and occasionally by a little more Common Salt. Then when 

 we get to the higher strata whose remains are yet left around 

 Carlisle, we get more abundant traces of salt, with sulphate of hrae 

 and carbonate of iron as before, until in the end the land sank 

 down and admitted the sea. With the changed conditions came 

 in sediment that formed rocks of a character quite different from 

 them we are more immediately concerned with. 



I have intentionally been a little discursive here, because I 

 wanted to point out that all our Red Rocks have certain features 

 in common, and that these features do not agree with the character- 

 istic features of deposits of marine origin, while they do agree 

 almost exactly with the features of deposits that have accumulated 

 in great inland lakes. We owe this generalisation to Professor 

 Ramsay, who has devoted much time and thought to the working 

 out of problems of this nature. Besides the evidence afforded by 

 the nature of the chemical deposits associated with the Red Rocks, 

 we get other evidence that is perhaps equally conclusive. Professor 

 Harkness, who did so much to work out the true relations of our 

 Red Rocks, has found casts, in sand and in mud, of the peculiar 

 hopper-shaped crystals of bay salt, in several places in Edenside. 

 These crystals take too long to form to have been developed on a 

 foreshore in the interval between the ebb of one tide and the flow 

 of the next ; or even in the longer interval between spring and 

 neap tides, so that their marine origin under ordinary conditions 



