4:16 Transactions. — Geology. 



Abt. LXX. — On a Deposit of Moa Bones near Motanau, North Canterbury. 



By Alexander McKay, of the Geological Survey Department. 



[Read before the Wellington Philosophical Society, 21st Jamiary, 1882.] 



During the past winter a flood occurred in Northern Canterbury -which 

 laid bare a deposit of moa bones near Motanau. This is exposed in the 

 banks of a small creek which forms the boundary between the properties of 

 Mr. Arkle and the Hon. William Robinson. Mr. Eobinson having reported 

 the discovery to Dr. Hector, I was sent to examine and collect from the 

 deposit, and am now permitted to lay before the Society an account of what 

 I saw and did. 



Where exposed the bones form a closely compacted bed, varying from a 

 few inches to 18 or 20 inches in thickness, and within a distance of 40 feet 

 they occur in gravel, sandy clay, plastic clay, and peaty lignite, the progres- 

 sion as stated being from east to west, there being a slight dip of the bone- 

 bed in that direction. In the banks of the creek the bone-bed is overlaid by a 

 deposit of gravel, sand, clay, and loam, to a depth of 10 or 12 feet, and has 

 at one time been covered to a much greater depth, as in the immediate 

 vicinity there is evidence that the bones must since their deposition have 

 been covered by at least some 50 or 60 feet of a deposit similar in character 

 to that which at the present time is seen to overlie them. Mr. Arkle 

 informed me that for many years past he had noticed bones in the bed of 

 this creek, which he now recognizes to be moa bones ; and to this gentleman 

 is due the discovery of the bone-bed, which he observed immediately sub- 

 sequent to the flood of last winter. Part of the deposit lying within his 

 property, Mr. Arkle kindly gave me permission to make such excava- 

 tions as I should deem necessary, for which I take this opportunity of 

 thanking him. 



The thickest part of the deposit appearing to lie on Mr. Robinson's side 

 of the creek, I opened a paddock on that side. In doing so 5 or 6 feet 

 of sandy loam was first passed through, in the lower part of which stumps 

 of trees were encountered of which no indications appeared at the surface. 

 Below this for the next 2 to 3 feet, a sandy bed with patches of gravel 

 was encountered, after which a bed of variable composition (quickly chang- 

 ing from sand to plastic clay) overlaid the stratum in which the moa bones 

 occur. The bone-bed over the area excavated varied from 1 foot to nearly 

 2 feet in thickness, and consisted of a closely compacted layer of bones, the 

 interspaces between which were filled by a soft tough clay. The whole 

 rested on a bed of well rounded gravel, the thickness of which could not, at 

 this place, be ascertained. All the bones, as far as the bed was excavated, 



