. 
TRANSACTIONS OF THE SECTIONS. “79 
the subject must explain. 1, How ice could move over so large ἃ portion of the 
North American continent, in a direction admitted to be tolerably uniform, allowing 
for slight deviations easily explicable as owing to irregularities in the original surface, 
and this without any mountain chain to give it forth. 2. How this ice was capable 
of ascending slopes and topping mountains of considerable height. 3. How, in such 
a valley as that of the Forth, there could be an ice-torrent of undeviating flow for 
many miles, and deep enough to envelope hills many hundred feet high 
Gold Mines of the Isthmus of Darien, Emigration to New Granada, and 
Canalization of the Isthmus of Darien. By Dr. CULLEN. 
Mr. John Hogg in reading this paper, stated that the author (Dr, Edward Cullen, 
of Dublin) intended to publish a new map of the Isthmus of Darien on a large scale, 
which would be of advantage to our knowledge of the geography of that part of 
America. 
The paper commenced with a geographical account of that Isthmus, which forms 
a territory of the Republic of New Granada; the most important part of which is 
that portion included between the Gulf of Wraba, or Darien, on the Atlantic, and 
the Gulf of S, Miguel del Ballano on the Pacific. In the author's opinion, nature 
had marked out this portion as the true medium of communication between the two 
oceans. A minute description then followed of this entire district, which enumerated 
some of the chief geographical characters. 
The gold mines of that Isthmus were likewise noticed. On the banks of the Cana, 
a branch of the river Tuyra, is situate the Mina Real, in the Cerro del Espiritu 
Santo, the richest mine that was ever worked. Dr. Cullen said, that for a number 
of years, the sums transmitted to Spain for the king’s Veintavo from that mine, 
averaged upwards of 33 millions of dollars per annum, giving upwards of 70 millions 
of dollars per annum for the whole produce. This he considered as a prodigious 
return, which completely throws into the shade the recent gold digging in Cali- 
fornia, where the produce seldom reaches one million of dollars per month, Besides 
the Cerro del Espiritu Santo, there are many mountains near Cana, very rich in 
gold, which have neyer been worked. Also, the author found in the Isthmus of 
Panama, auriferous soil in many places, 
As a suitable district for emigration, the territory of Darien was detailed as offer- 
ing brilliant prospects, and possessing excessive fertility combined with great geo- 
graphical advantages. The lands set apart by the Republic of New Granada for 
colonization, consist of the table-lands and elevated valleys of the Cordilleras of the 
Andes, where the soil is very rich, and the climate temperate ; the thermometer 
during the year ranging from 50° to 80° Fahrenheit. 
The paper concluded with some observations on the canalization of the Darien 
Isthmus, and Dr. Cullen stated that on his return from the interior of Darien, he 
ascended the Chuquanaqua and Savana Rivers; these, but more particularly the 
latter, in his estimation, afford the most direct and feasible mode of communication 
with the Atlantic, No bar exists at the mouth of the Tuyra, or of the Savana; nor 
is there any difficulty in the navigation of the Gulf of San Miguel on the Pacific, nor 
~ on the coast of the Atlantic. 
On the Succession of Strata and Distribution of Organic Remains in the 
Dorsetshire Purbecks. By Prof. Epwarp Forses, F.R.S, 
_ During the autumn of 1849, Professor E. Forbes was deputed by the Director- 
General of the Geological Survey, Sir Henry De la Beche, to examme the organic 
remains of the Purbeck strata in Dorsetshire, and to investigate their distribution in 
situ, acting in cooperation with Mr. Bristow, the officer engaged in constructing the 
geological map of the district. The results of this inquiry were so novel and curious, 
that it was thought by the Director-General desirable, before publication in an ex- 
tended form, to lay them before the British Association, in the hope that-by such a 
course attention may be directed to similar phenomena in freshwater formations in 
; other districts. Our knowledge of the Dorsetshire Purbecks has been derived chiefly 
from the memoirs by Professor Webster, Dr. Fitton, Sir H. Dela Beche, Dr. Buckland, 
