The ridges run north and east from Messines, above sea-level at its highest point, past Clapham Junction at the west end of the Gheluvelt plateau, from Ypres at and Gheluvelt, above , to Passchendaele from Ypres at , declining from there into the plain further north. Gradients vary from negligible to at Hooge and at Zonnebeke. Underneath the soil is London clay, sand and silt. According to the Commonwealth War Graves Commission criteria of "sand", "sandy soils" and "well-balanced soils", Messines Ridge is "well-balanced soil", drained by many streams, canals and ditches, which needed regular maintenance. Since the First Battle of Ypres in 1914, much of the drainage in the area had been destroyed by artillery-fire, although some repairs had been achieved by army Land Drainage Companies brought from England. The area was considered by the British to be drier than Loos, Givenchy-lès-la-Bassée (Givenchy) and Plugstreet (Ploegsteert) Wood further south.