HuTTON. — ■Geoloijy of the TreUssick Basin. 897 



The following section of the upper beds of the Waipara 

 System is exposed in this gorge : — 



6. Limestone .. ... ... 30 feet 



5. Marl ... .. ... 10 „ 



4. Limestone ... ... ... 50 „ 



3. Calcareous grit ... ... 4 ,, 



2. Green sandstone ... ... 40 ,, 



1. Marl ... ... .. 150 „ 



No. 3 contains rolled fragments of volcanic rocks, and in the 

 lower part of the marl (No. 1) there are several layers of 

 calcareous concretions. On the south side of Prebble Hill the 

 limestone is divided into two parts, the lower of which is 

 composed of comminuted fragments of Bryozoa, HydrocorallinaB, 

 etc., forming what is called a coralline limestone, thus differing 

 altogether from its normal character, and resembling the upper 

 limestone, presently to be described. The dip of the upper beds 

 just above the gorge is 40° N., increasing at the gorge to 56"^ N. 

 In the lower part of Broken Eiver the greensands exhibit 

 their greatest development (PI. XXV., Section I.). I estimate 

 their thickness here at about 850 feet, the dip being tolerably 

 uniformly 25° W. They are covered in the Porter Eiver by about 

 200 feet of grey marl, upon which rests a stratum of brownish 

 green sandstone 20 feet thick. Then comes 20 feet of arenaceous 

 marl, and then the limestone, about 100 feet in thickness at the 

 second gorge. All these beds dip 25° W., but south of the 

 Porter Eiver the direction of the dip rapidly changes, as the 

 beds sweep round through a right angle to the first gorge, and 

 form Prebble Hill. I did not measure these beds in the Broken 

 Eiver, neither did I examine them closely in their northerly 

 extension, although from the top of Flock Hill I saw, in the 

 valley to the east, what I took to be a good exposure of the 

 marl. The dip of the limestone at Flock Hill is about 25° W. 

 (PL XXV., Section II.). 



At Parapet Eock, on the West Coast Eoad, the limestone is 

 compact and flaky, grey in colour, but weathering first red and 

 then white. In the bed of Murderer's Creek it is underlain by 

 about 30 feet of laminated calcareous sandstone, containing a 

 bed of shale about 1 foot in thickness. The marl is not seen 

 here, for to the north the greensands have been faulted upward 

 against it. The limestone at Parapet Eock, on the right bank 

 of Murderer's Creek, dips 77° E.S.E., but on the left bank it 

 dips 40° S., gradually turning round to the west towards Flock 

 Hill. The next place where I examined these rocks was at the 

 upper gorge of the Broken Eiver, near Sugarloaf Hill, where the 

 same fault that occurs at Pai'apet Eock crosses the river (PI. XXV., 

 Section II.). Here the rocks have been so much disturbed by the 

 fault that I was not able to interpret them intelligently. At the 



