Professor Bucrland on the Bones of Mastodon, Sscfrom Ava. 383 



imbedded ; these are composed of small round grains and pebbles of white 

 quartz and various quartzose and jasper pebbles, strongly united together by 

 a cement of carbonate of lime, and sometimes by hydrate of iron : where this 

 iron is very abundant, it alTords concentric ochreous concretions, resembhng 

 Aetites, dispersed irregularly through the breccia. The masses of calcareo- 

 siliceous conglomerate that adhere thus to the bones, do not appear to have 

 been separated by violence from any mass or stratum of solid stone, but to be 

 merely small local concretions attached to these bones. There are other cal- 

 careous concretions that contain no kind of organic nucleus, but are composed 

 of precisely the same materials as those which are formed around the bones, 

 and present many of the irregular shapes of the tuberous roots of vegetables ; 

 some of them also have the elongated conical form of slender stalactites or 

 clustered icicles, a form not unfrequently produced in beds of loose calcareous 

 sand by the constant descent of water along the same small cavity or crevice, 

 to which a root or worm-hole may have given the first beginning : some of 

 these appeared in the cliffs just mentioned near Wetmasut. I have seen 

 similar elongated and pseudostalactitic concretions disposed at right angles to 

 the beds of sand, and descending vertically by the side of each other, like the 

 roots of carrots and parsnips, to a depth of nearly two feet, displayed in the 

 section of the cliff near Finale between Genoa and Nice, and I have also a 

 collection of the same kind from the calcareous sand-beds of Bermuda ; their 

 form and position in the sand caused them to be sent home, under an idea 

 that they were petrified roots*. Neither the insulated concretions from Ava, 

 nor those adhering to the bones, contain traces of any kind of shells : they 

 also differ mineralogically from all the specimens of tertiary and fresh-water 

 strata in this collection. 



Among the most remarkable of these strata is a fresh-water deposit of blue 

 and marly clay, containing abundantly shells that belong exclusively to a large 

 and thick species of Cyrena ; and a dark-coloured slaty limestone containing 

 shells which Mr, Sowerby has identified with some of those that occur in our 

 London clay. There is also, from the hills opposite Prome, granular yellow 

 sandy limestone containing fragments of marine shells, and much resembling 

 the calcaire grossier of the environs of Paris ; and from the same neighbour- 



* Dr. Fitton, in his excellent account of some geological specimens from the coasts of Australia 

 (London, 1826), describes many similar examples of stalactite. shaped and other irregular calca- 

 reous concretions, in the sandy strata that occur on many parts of those coasts. He also gives 

 references to authors who have described similar cases in other countries ; viz. to Dr. MacCulloch, 

 who has described them as existing in Perthshire, Dr. Paris in Cornwall, Captain Lyon in Africa, 

 and other writers. 



