Sketch of Dr. A. R. C. Sehvyn.—Ami. 3 
He is credited with no less than sixteen geological maps 
prepared either entirely by himself, or, in conjunction with, 
his chief, Sir A. C. Ramsay, or the Director-General himself, 
or again, with such well-known men on the geological staff 
as Ed. Hull, W. T. Aveline, W. W. Smythe, J. Phillips, H. 
B. Howell and his particular friend and colleague J. B. Jukes. 
The geological sheets or maps of Leominster, Montgomery, 
Market Drayton, Harlech, Banger, Bardsey and Machynlleth 
are ascribed in part or in whole to the subject of this brief 
sketchi. 
It was during his field work in Wales that Selwyn dis- 
covered the unconformity between the lowest Cambrian and 
the older series of schists underneath. In this classic country 
of the Welsh succession, Selwyn and Ramsay worked together 
and of one of those "Councils" on the Shropshire sheets the 
latter wrote at the time in his field note-book : — "Held a coun- 
cil with Selwyn on the Shropshire sheets, etc. his work there 
and here (Xorth Wales) is the perfection of beauty." "One of 
the most striking sections of the whole series of sections pub- 
lished by the Geological Survey," writes Sir Archibald Geikie 
later, "runs from the top of Snowdon parallel with the Llan- 
beris valley to the Menai straits at Llanfair, whence it was 
afterwards continued across Anglesey. On the other side it 
was prolonged south-eastwards into the country mapped by 
Selwyn, and was carried by him into Merionethshire, across 
Cynicht, Moel Wyn and Aran Moddwy, and was continued bv 
Aveline across Montgomeryshire." Sir Archibald adds : — 
"The geological structure is portrayed by Ramsav and Selwyn 
with a boldness and vigour, and at the same time with an 
artistic feeling, which had hardly been equalled in geological 
section-drawing." 
In 1845 Selwyn worked out the complicated geology of the 
volcanic distric of Cader Idris in North Wales : the summer 
of 1846 he was engaged in mapping out the rock formations 
in the Dolgelly region, whilst Aveline was tracing the boun- 
daries of the Silurian series from Llanbrynmair eastward to 
the Church Stretton and the Longmynd. Ramsay accompan- 
ied Selwyn and records : — "Glorious days and glorious scen- 
ery, out with Selwyn along the front of the Cader Cliffs." 
He adds : — "Selwyn's work good." Testimony from such 
