TY - SER AU - Barrett, W.H. TI - The mechanical composition of the London tertiaries in the neighbourhood of Harrow-on-the-Hill KW - Mechanical composition - Tertiary period - London KW - Heavy mineral analyses - Pikes peak and silver plume granites - London N2 - Extract There have been in the past few years opportunities, which are not likely to recur, for collecting fresh and unweathered samples of the Upper and Lower members of the LondonTertiary series in the neighbourhood of Harrow. It therefore seemed to be worth while making a series of mechanical analyses of these samples for comparison with analyses which have been made of samples from the same formations in the other parts of the London basin ER -