SILURIAN PERIOD 
And streams and rivers, brisk through vale and plain, 
Bear down the surface wreckage to the main. 
The sea herself joins with the vandal hosts, 
Scooping out caves, and breaking down the coasts. 
Whilst slowly here and there some lands subside, 105 
And disappear beneath the advancing tide. 
But compensation conies : the powers that be 
Conspire for land as well as for the sea ; 
Or strange had been our planet's history ; 
And void of beast to walk and bird to fly no 
Our globe had spun as fish-bowl in the sky. 
The sea that conquers here is beaten there, 
As from the depths raised bottoms greet the air ; 
Slowly but surely through the billows thrust, 
By pressure of the cooled and shrinking crust. 1 1 5 
And spoils brought down by rivers to the shores, 
And shot in layers upon the briny floors, 
Thickened and hardened rise in time again 
As solid grounds to mock the insatiate main. 
And deltas, shoals, and bars of mud and sand 120 
Their spoils all heap to compensate the land. 
And though through inland scene, and by the shore, 
Change and decay are ever to the fore ; 
Still does their action, ceaseless night and day, 
For land's approaching glory pave the way. 125 
'9 
