REPORTS OF RESEARCH COMMITTEES. 347 



Round the west and north-west coast of the Territory the 

 laterite-porcellanite formations are practically unbroken. They 

 rise towai'd the interior as a gentle inclined plane, the slope of 

 which exceeds the sloipe of the comntiy, so that as we go inland 

 the laterite-capped peneplain gets more and more dissected, and 

 the laterites occur only as disjointed cappings of mesas, which 

 occur always at the same altitude in the same district indicating 

 former continuity. The laterites to-day are undergoing rapid de- 

 nudation. Two factors have contributed to the dissection and 

 destruction of the laterites and porcellanite sheet: (1) the arching 

 up and elevation of the country, coupled with (2) an increase 

 iu rainfall. 



The first indication of the return of the wetter climate was the 

 formation of patcheis of bog-ircii ore in depressions. Patches of 

 this frequently cap porcellanite. When they formed the drainage 

 was still disintegrated. 



As regards evidence oif the alluvials, great areas of these are 

 shown around the estuaries of the Alligator River, in the north- 

 west comer of the Territory, at the mouth of the Adelaide River, 

 and the mouth of the Mary River. Great areas of swampy coastal 

 lands exist here, composed mainly o^f raised post-Tertiary alluvials. 

 There is not nearly as much alluvial at the mouths oif the Daly 

 and Victoria. This is because the axis of recent elevation runs 

 from Port Darwin east through Arnheim Land. The recent ele- 

 vation along this axis has caused a diversion of streams. It 

 appears that originally the VictoVia flowed north through Dela- 

 mere into the Flora and the Flora probably flowed into the 

 Adelaide. The course of the stream was approximately north- 

 south. Snowdrop Creek, now a branch of the Catherine, was a 

 branch of the East Alligatoi. Thus, the Van Diemen Gvilf allvi- 

 vials are very extensive. Thisi elevatiom co'mmenced in the 

 Tertiary and continues to the present time. Consequently the 

 east-west Daly has been formed ; the Victoria. River has taken 

 a new channel through the gorge, flowing now west-north-west 

 from Gregory's Camp instead of north bv Sullivan's Creek into 

 the Flora. 



The elevation of the Northern Territory was accompanied by 

 depression west of the Territory, and alsoi over a portion of the 

 Gulf of Carpentaria area. In the latter region the depression 

 has ceased and yielded to elevation, except in the extreme ncrth- 

 west about Cape Wilberforce. 



Thus, raised beaches of very recent age abound along the coast 

 at Darwin, Van Diemen Gulf, Bowen Strait, the Pellew Islands, 

 and Mc Arthur Coast, &c. , and a vast extent of recent Tertiary 

 rocks exist east and south of the Gulf ol Carpentaria. 



