148 ASCENT OF THE FITZ-ROY. 



reach, which extended barely a quarter of a mile, in 

 from a S. by E. to a S. by W. direction ; and varied 

 in width from one to two hundred yards. We now 

 entered a lake-like reach of the river, trending south 

 for a mile and a quarter, having a breadth of about 

 a hundred yards, and a depth in many places of 

 twelve feet ; being twice that which we had usually 

 found in any of the lower reaches, with scarcely 

 any stream. Soon after entering this remarkable 

 sheet of water, we noticed a rock formation in its 

 western banks ; this we found to be a coarse- 

 grained red sandstone, with fragments of quartz, 

 and extended for nearly a quarter of a mile along 

 the edge of the water. Over many parts of it was 

 a coating of a dark and metallic appearance, about 

 three inches thick ; and the surface in places pre- 

 sented a glazed or smelted appearance. Mr. Darwin, 

 in his work upon volcanic islands, page 143, alludes 

 to this formation, under the head of " Superficial 

 ferruginous beds," and thus concludes his observa- 

 tions : — "The origin of these superficial beds, 

 though sufficiently obscure, seems to be due to allu- 

 vial action on detritus abounding with iron." 



As we proceeded along this canal, for such was 

 the appearance of the reach we were now ascending, 

 we surprised a small party of natives. They were at 

 the water's edge, beneath a high mound of loose white 

 sand, over which the children were some time in 

 making their escape, struggling and screaming with 

 anxiety and fear, as they half buried themselves be- 



