45 



There is a marked absence of tufaceous sands, and it is 

 upon this circumstance chiefly that I infer the lower zone marks 

 the epoch immediately preceding the later volcanic eruptions. 

 At any rate its deposition occurred during a time of repose, 

 as the clays are not impregnated with the oxide of iron, which 

 so distinctly colours the upper members. 



The remains of leaves (which are those referred to in my 

 former letter to this society) imbedded are preserved to us in 

 a carbonized form. This I consider is a very important feature, 

 for among the thousands of leaves exposed by me in the 

 upper beds, there was not one preserved in a carbonized form ; 

 only the ochreous casts remained. 



Unlike the shifting beds at Windmill Hill, Launceston, the 

 laminations are conformable with each other, and they dip 

 very slightly to the north-west, i.e., — in an exactly opposite 

 direction to the series of greywacke beds which flanks the 

 northern extremity. 



Mr. Gunn also"^ informs me that the lignite appears on 

 marshy ground near to the Western Tiers. 



Generally we may indicate this zone as a deposit formed 

 prior to the more recent volcanic eruptions. 



MIDDLE ZONE. 



The Middle Zone is well represented by that series of beds 

 which forms the Windmill Hill, Launceston. 



They are chiefly composed of shifting beds of clay and 

 tufaceous sand. These beds admirably illustrate the mode in 

 which mud and sand is precipitated in running water. 



Wedge-shaped beds are cut through and overlie similar 

 beds, in the most wanton unconformity. 



They generally present a wavy horizontal appearance, but 

 they intersect each other repeatedly throughout the series, in 

 a manner difficult to describe. 



Yery probably these beds were thrown down in the channel 

 of running water from the upper lake, by the conflict of two 

 currents meeting each other at right angles. 



From the appearance of that valley running from First 

 Basin to Glen Dhu I infer that a considerable stream, emerg- 

 ing or flowing by way of that rocky fissure, which forms the 

 channel of the South Esk, w^ould be diverted into Glen Dhu by 

 an obstruction at that romantic gorge which now forms its 

 narrow outlet. The division of a powerful volume of water 

 from this rock basin in the direction of Glen Dhu, and meeting 

 the main body of water by way of the North Esk valley, would 

 no doubt help to precipitate the mud and sand held in sus- 

 pension by both streams. 



This supposition would also account for the peculiar horse- 



