THE SUNKEN ROADS OF THE SOMME.
[To THE Minos or THE " SPECTATOR.")
Sra,—Major Stuart Love, R.E., in his letter re above published in the Spectator of March 23rd, assumes that " the gullies which contain these roads " have been formed first, and the roads laid afterwards. It seems to me that the roads are the cause of the gullies by a combination of natural and artificial (traffic) causes. One cannot spend over two years travelling on foot in the Somme district and the chalk country without noticing the sunken roads, and I have theorized as to their formation as follows. With little or no excavation " road veneer " is laid down. Traffic crushes and wears this down or forces the softer material up through the interstices of the " road veneer." Wet weather comes, and with the help of further traffic this dust is churned into sloppy mud. Where the surface of the ground is level this mud very slowly disappears from the road; but, in the hilly parts, the mud escapes more quickly down the side channeld on to the low-lying ground. My opinion is that the depth of the gully is determined by the age of the road and the steepness of the incline. The cases where " the depth of the same road will vary from twenty fret to nothing in less than a hundred yards, in the same kind of soil," are exceptional, and cannot dispel the theory of attrition by traffic. Assuming that the cases referred to are in level country, it seems to me that the explanation is that the mud has dis- appeared down fissures or into caves in the chalk below.—I am,
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