72 PROFESSOR T. W. EDGEWORTH DAVID AND MR. G. SWEET. 



Inside the jagged corrosion zone 0.2. B. is an intermittent smooth white zone of 

 erosion whei'e the surface of the breccia is being continually pounded and rubbed 

 by shingle rolled over it at high tide by waves breaking against the Hurricane Bank. 

 (See Plate 17.) Next comes the zone O.2.D. (See Plate 17 and Section C-D.) 

 This, as stated on the index, forms a low wall or steep slope extending from 2 or 3 

 feet below high water up to 2 or 3 feet above. The case at the S.W. end of Telele, 

 where an outlier of this breccia attains a height of over 9 feet above high water, 

 has already been mentione;!. This zone forms in place low ramparts with 

 re-entering angles and outlying rugged pinnacles. The general aspect of this part 

 of the breccia is shown in the upper figure of Plate D. 



The manner in which delicate laminre of Lithothamnion occur as cementing material 

 in this breccia, up to heights of from 1 to 2 feet above high water, is proof that 

 even this upper part of the breccia was formed originally under water, and the 

 presence in situ of the Lithothamnion shows that it was formed not much above the 

 level of low tide. The reef breccia marked 0.2. E. is other than and in some 

 cases newer than 0.2. A., O.2.B., O.2.C. or O.2.D. It is typically developed on the 

 main island just beyond the stretch of sand on the lagoon beach north of the 

 village of Fongafale. It is also developed in places to the south of Fongafale, as near 

 Luamanife and to tlie south of Fuagea, &c. 



We may now pass on to consider the strata mostly, if not wholly, newer than the 

 breccia sheet. L.2.A. is an old conglomerate formed on a former shore of the lagoon, 

 and composed of well-rolled pebbles of coral more or less cemented together. This 

 rock becomes almost a sandstone in places. It is typically developed at the main 

 island about 230 yards easterly from the Mission Church. Thence it trends in a 

 northerly direction close to the path on the line of Section 10 A-B of Plate 9. 

 We think that on the main island it marks an old shore line of the lagoon or possibly 

 a channel in the old Hdiopora ccernlea reef, probably the former. It is about 4 feet 

 in thickness. It is also typically developed at the N.W. end of Amatuku. (See 

 Plate 12, Sections 1 and 4, Amatuku.) The conglomerate is bedded, the strata 

 dipping W. 30^ S. at 1 in 15. At its base the conglomerate rests upon a hard 

 foraminiferal Lithothamnion sandstone. Tlie lower figure on Plate D shows the general 

 aspect of this old lagoon conglomerate at Amatuku. (The large trees are Fetau trees. ) 



The top of this conglomerate at Amatuku is fully G feet above high water, as 

 shown on the Section. As the conglomerate is fairly firmly cemented, and as no 

 such cementing can now be seen in progress in the atoll above high water, and, 

 indeed, very little above low water, we are of opinion that this evidence, like that 

 afforded by the raised Hclioj^ora cccndea reef and the outliers of reef-breccia, implies 

 a downward movement of the shore line of not less than 6 feet in this case, and as 

 there are water-worn pebbles of breccia in the conglomerate, this elevation must have 

 been subsequent to the consolidation of the breccia sheet. 



Another interest which attaches to this old lagoon conglomerate is that it forms 



