compete successfully
with weeds . . . . . . . . . . . . . . . . . . . . 94, 95

45. A plot of wheat left untouched since 1882 at
Rothamsted has now become a dense thicket.
_Phot._ Lionel Armstrong . . . . . . . . . . . . . . 97

46. A badly drained wheat field . . . . . . . . . . . . . 99

47. Highly cultivated sandy soil in Kent . . . . . . . . . 103

48. A Surrey heath . . . . . . . . . . . . . . . . . . . . 105

49. Woodland and heather on high sandy land, Wimbledon
Common. _Phot._ R. H. Carter . . . . . . . . . . . 107

50. Poor sandy soil in Surrey, partly cultivated but mainly
wood and waste . . . . . . . . . . . . . . . . . . . 109

51. Open chalk cultivated country, Thanet . . . . . . . . 113

52. Cliffs at the seaside, Manorbier.
_Phot._ Geological Survey . . . . . . . . . . . . . 117

53. Cliffs in inland district, Arthur's Seat, Edinburgh.
_Phot._ Geological Survey . . . . . . . . . . . . . 119

54. Model of a stream . . . . . . . . . . . . . . . . . . 120

55. The bend of a river . . . . . . . . . . . . . . . . . 121

56. The winding river--the Stour at Wye.
_Phot._ R. H. Carter . . . . . . . . . . . . . . . . 123

57. Sketch map showing why Godmersham and Wye arose
where they did on the Stour . . . . . . . . . . . . 126

58. Ford at Coldharbour near Harpenden.
_Phot._ Lionel Armstrong . . . . . . . . . . . . . . 127

The photographs of the pot experiments are by Mr Lionel Armstrong.

{xi}

INTRODUCTION

The following pages contain the substance of lessons given at the
village school at Wye to the 4th, 5th, 6th and 7th standards (mixed)
and at St George's School, Harpenden, to the 3rd form. There is,
however, an important difference between the actual lessons and the
book. The lessons had reference to the soils round about the village,
and dealt mainly with local phenomena, general conclusions being only
sparingly drawn; while in the book it has been necessary to throw the
course into a more generalised form. The teacher in using the book
will have to reverse the process, he must find local illustrations and
make liberal use of them during the course; it is hoped that the
information given will help him over any difficulties he may experience.

This necessity for finding local illustrations constitutes one of the
fundamental differences between