■^6 SuKARSHV, Recent Traverlin J-'^oDiid/ioiis. Yass. [\„Vx'xxvM 



The original roots finally die. and lielp to lorni the solid 

 material which may he seen between the rule and th»- com- 

 paratively freshdooking roots. 



" The growth of the travertin this year (1919) is v^ery rapid, 

 as the rainfall has been very light and evaporation abnormal, 

 the result being that, as the spring issues very highly charged 

 with lime, anci flows over such a mass of moss, grass, roots, 

 and watercress, that it is all evapoiated before it travels far, 

 and all the organic matter is left in sifii coated and cemented 

 together into a porous limestone." 



In the Oaky Creek locality the lime is leached out of the 

 Devonian limestones. 



Travertm, Ravenswood Creek, portion yq, parish of Boam- 

 bolo, Yass. — A small specimen of this travertin is exhibited, 

 which is typical of a deposit that may be traced along Ravens- 

 wood or Hall's Creek for about two miles. 



The specimen in this instance is composed of incrusted mint, 

 which thrives very luxuriantly all along this creek. In many 

 places the mint is crowded out by watercress and Chara, both 

 of which are also travertined and help to form solid masses of 

 calcareous rock. In this locality I have also picked out lime- 

 incrusted fruits and leaves of Eucalyptus, shells of the pond 

 snail Limncca, and portions of insects. This locality has also 

 a more solid deposit, which L. F. Harper * noticed is often 

 ripple-marked. The lime in the Ravenswood area is leached 

 Out from the Silurian limestones which outcrop thcTc. 



Mr. Harper also refers to another elass of Secondary Lime- 

 stone : — " A totally different class of deposit of recent age is 

 found on the slopes of the Devonian limestone outcrops. It 

 consists of a limestone breccia, usually about eight inches 

 thick, which owes its origin to a re-cementing of the shale and 

 limestone talus. The breccia rests on top of shales with 

 chocolate-coloured bands and tuffs, and is quite hard and 

 compact in places, whilst in others it is more friable. "f 



A very similar formation to the above is to be noticed in 

 the Silurian deposits at Hatton's Corner, ^'ass. 



Addendum on Tkavektin in General, hv !•. ( ii.U'Man, .\.L.S. 



Deposits of travertin on vegetation and terrestrial debris 

 are more often found in the later formations, 'iVrtiary and 

 Post-Tertiary. The present interesting occurrence reminds one 

 of the deposits formed from the driiiping wells of Knarcs- 

 borough, in Yorkshire, and \\\ Derbyshire. Sharpe has 



* L. F. Harper, Rcc. Gcol. Surv. N. S. NValcs, vol. ix., 1909, p. 11. 

 ■f l.oc. supra cit., p. 11. 



