LOWER GREENS AND. 31 



which form so conspicuous a feature in the upper part of Black- 

 gang Cliine, and to which the name sand-rock is singularly- 

 applicable. Three distinct bands of this deposit occur, namely, the 

 beds referred to by Fitton as the fourth, third, and second sand- 

 rock. The second or lowest occupies the beach from Rocken End 

 for a distance of 200 yards northwards ; but is partly concealed 

 by slips of Chalk and Greensand. Thence it may be traced 

 continuously to the top of the cliff 500 yards west of Cliff" Terrace, 

 where it is seen overlying the great ciay-bed previously described. 

 The third or middle bed, and the fourth at the top of the series, 

 may be traced from the chalybeate spring to a point on the east 

 side of Cliff Terrace, where they reach the top of the cliff". 



The following descending section of the series was made in the 

 heighbourh od of the chalybeate spring, 600 yards south-east of 

 Southland House : — 



Section of the Sand-7'ock Series near the Chalybeate Spring. 



Carstone (for details, see p. 57). Ft. 



Grey sand with wood, large concretions, and seams of clay; a 

 line of quartz pebbles at the base - - - - 20 



Grey and yellow sand interlaminated with clay - - 7 



Current-bedded yellow sand-rock, with wood ; thins away 

 southwards (4th sand-rock of Fitton) - - - 14 



Laminated sand and clay, with wood ; throws out the chaly- 

 beate spring - - - - - - 22 



A variable bed ; contains clay with partings of sand, some- 

 times nearly all sand, and passes down into - - 16 



White sand-rock (3rd sand-rock of Fitton) about - - 25 



Variable sand and clay, with a line of nodules about the 

 middle - ------ 60 



White sand-rock (2nd sand-rock of Fitton) - - - 20 



184 



The interlaminated sands and clays in this section are identical 

 in character with the '• foliated bed " 56 feet thick of the Compton 

 Bay section (|)p.22, 23), und like it throw out chalybeate water, 

 derived doubtless from the decomposition of iron pyrites. 



The Chalybeate or Sand-rock Spring was first noticed about the 

 year 1800. It was found to flow at the rate of 100 to 150 

 gallons a day, and gave the following analysis* : — 



16 ounces yielded : — 



Carbonic acid gas, 3 cubic inches. 



Solid ingredients, dried at 180°, 80"5 grains. 



Grains. 



Sulphate of iron - - - - - 41 '4 



Sulphate of alumina - - - . -31*6 



Sulphate of lime, dried at 160° - - - -10-1 



Sulphate of magnesia - - - - - '6' % 



Sulphate of soda - - - - - -16" 



Chloride of sodium - - - - - 4 • 



Silica - - - - - - . •'] 



107-4 



Temperature, 51°. Specific gravity, 1*0075. 



* Dr. Marcet, Trans. Geol. Soc, Ser. 1, vol. i. p. 213. 1811. 



