At El Kenîsa, a promontory jutting out into the lake, sandstones showing shell-borings occur at a height of 14 metres above sea-level. Between Dimê and the lake a calcareous sandstone contains many borings, 66 metres above the lake-level, or about 22 metres above sea-level. [Illustration: PLATE XIII. BORINGS IN FALSE-BEDDED SANDSTONE, TWO KILOMETRES SOUTH OF DIMÊ.] (β) _High level borings._ Further west, but at a considerably higher level, borings are again met with. In this case a hard compact limestone, forming a dip-slope surface on the top of the lower cliff of the Qasr el Sagha series, was found pierced with borings, similar in character to those of the lower level. The exact locality where these high level borings were observed is 14 kilometres west of the western end of the lake and 16 kilometres north-east of the eastern extremity of Gar el Gehannem. The height was determined as 156 metres above the Birket el Qurûn, or 112 metres above sea-level, and we have every reason to believe these figures to be approximately correct. Up to the present time borings at this altitude have not been met with in any other locality. At first sight it seems surprising that the occurrences should be so limited, but it should be remembered that only in those cases where borings were made in the very hardest and most durable rocks could they have been preserved to the present time. Considering the amount of denudation which has taken place in the area since the Pliocene period it is surprising that any of the rocks which formed the actual surface of the country at that date should still be preserved; and in all probability the comparatively few records that exist to-day owe their preservation to the protection afforded by superficial deposits. Under the present rigorous desert conditions, when the whole surface is subjected to continual and rapid changes of temperature, and every exposed rock is being worn down by the natural sandblast, it must be admitted that in a comparatively short time every trace of the borings now exposed will have been removed. At the same time the denudation of superficial deposits will probably lay bare other bored rock-surfaces, and the conserving nature of drift sand itself where accumulated to even a limited degree must not be forgotten. _L._—=Gravel Terraces: ? Upper Pliocene.=