19 
DISCUSSION ON THE ORIGIN OF THE TRIAS.* 
Mr. T. H. Holland referred to certain phenomena in the 
Rajputana desert that supported Mr. Lomas's views with regard 
to the processes of concentration in arid regions. He referred 
to the separation of the finer angular sands (which were carried 
bodily in the wind and became deposited in the North Eastern 
area, where the force of the wind was diminished) from the 
rounded grains formed by the rolling of grains too heavy to be 
carried by the wind. With the finer material in the neighbour- 
hood of Bitraner, Mr. La Touche has described the occurrence 
of undamaged tests of foraminifera, which must have been 
carried in the wind some 500 miles from the Kathiawar Coast. 
Mr. Holland also described the occurrence of the silt beds 
filling in hollows in the Archaean surface, having a general plano- 
convex lens shape, and being charged with salt, beds of gypsum, 
and concretionary nodules of carbonate of lime such as Mr. 
Lomas had described in connection with the Trias. He was not 
prepared to admit that the features of the British Trias were due 
only to wind action, but in the main, they were due to the con- 
ditions prevailing in desert regions, where, during monsoon 
seasons, there may be a heavy rainfall for a limited period, with 
rivers in flood, and all the usual phenomena of river action. 
Prof. J. W. Gregory dealt with the conditions found in 
the Australian desert, and said that the deposits now forming 
these reminded him of the Trias of Cheshire. 
Prof. Grenville A. J. Cole said that in dealing with the 
British Trias we must never forget the great sea eastward, and 
the likelihood of the establishment of a monsoon system upon 
its margin. The geographical conditions seemed well suited 
for this, and an intense rainy season lasting, say, three months, 
might easily, year after year, sweep down and redistribute 
materials which remained dry for the other nine months. Sheets 
of pebbles without well defined water channels are compatible 
in such cases with general conditions of desiccation. 
* At the York Meeting of the British Association, following the 
papers by Professor Bonney and Mr. Lomas. 
