[ 392 ] 



Livingstone for that pur- 

 pose. Among the angular 

 fragments are round stones 

 from the size of a golf-ball 

 to 18 inches in diameter. 

 They preserve their globu- 

 lar form as they weather 

 or decompose, and what 

 looks like the segment of 

 a bomb is often to be 

 found ; but when smaller 

 balls were broken up they 

 always proved to be solid. 

 In close connexion with 

 the loose material are 

 beds of grit with included 

 blocks of basalt, and a de- 

 posit of white calcareous 

 tufa. 1 Large quantities of 

 both have been removed, 

 but the extent of the 

 deposits has not been 

 ascertained, nor has the 

 depth been explored be- 

 yond about 8 feet. In 

 the accompanying section 

 (fig. 2) a bed of rock- 

 basalt about 3 feet thick 

 overlies a gritty bed con- 

 taining blocks of basalt. 

 The influence that such 

 patches of loose material 

 would have had in deter- 

 mining the course of the 

 gorge is obvious. 



Solid basalt appears in 

 the bed of the Maramba 

 near the quarry ; it shows 

 on the flat to the east of 



1 [This material, called 'tuff' 

 in the original paper, and re- 

 ferred to by Mr. Lainplugh in 

 the Discussion, proves, on ex- 

 amination of specimens which 

 have reached England since, 

 to be calcareous tufa derived 

 from decomposed basalt. The 

 'grit' is disintegrated basalt. 

 — T. C, April 20th, 1909.] 



