For many years I have been interested in the colloidal nature of coal. As long ago as 1914, in discussing the coal resources of Korea State in the Central Provinces of India, I suggested that the bright bands of the Korea coals are colloidal. It is suitable to quote here the exact words used:—

During my visit to Malaya in 1938, for the purpose of reporting to the High Commissioner upon the mineral industry of that country, I noticed in cuttings at two places exposures of banded rocks of alternating light and dark tints that recalled the varved sediments of other parts of the world. As such rocks have not hitherto been described from Malaya, and as varved sediments are everywhere considered to be of much interest, a brief note upon these Malayan occurrences seems desirable, in case they should prove to be of similar origin.

The Upper and Lower Estuarine Series in the East Midlands contain a number of layers of carbonaceous shale or clay and in many cases roots can be seen extending downwards in the underlying deposits. Except for plant-remains these carbonaceous layers are for the most part barren. Samples supplied by Mr. Linsdall Richardson were examined by Professor Harris and found to contain small fossil plants of types which appeared determinable and thus of possible stratigraphic value. Mr. Richardson collected other samples which he sent together with stratigraphic notes; Professor Harris handed me the material for investigation.

The investigation of the possibility of late-glacial sea-levels at 190 feet (58 m.) and 140 feet (42 m.) has entailed the reading of a vast quantity of literature dealing with glacial observations. The following is an account of some facts gathered and some ideas arising from these readings.