inches　in　thickness。　　Beneath　this　lay　coarse　clayey　earth　full　of
  flints；　like　that　in　any　of　the　neighbouring　ploughed　fields。　　This
  coarse　earth　easily　fell　apart　from　the　overlying　mould　when　a　spit
  was　lifted　up。　　The　average　rate　of　accumulation　of　the　mould
  during　the　whole　thirty　years　was　only　。083　inch　per　year　（i。e。；
  nearly　one　inch　in　twelve　years）；　but　the　rate　must　have　been　much
  slower　at　first；　and　afterwards　considerably　quicker。
  The　transformation　in　the　appearance　of　this　field；　which　had　been
  effected　beneath　my　eyes；　was　afterwards　rendered　the　more
  striking；　when　I　examined　in　Knole　Park　a　dense　forest　of　lofty
  beech…trees；　beneath　which　nothing　grew。　　Here　the　ground　was
  thickly　strewed　with　large　naked　stones；　and　worm…castings　were
  almost　wholly　absent。　　Obscure　lines　and　irregularities　on　the
  surface　indicated　that　the　land　had　been　cultivated　some　centuries
  ago。　　It　is　probable　that　a　thick　wood　of　young　beech…trees　sprung
  up　so　quickly；　that　time　enough　was　not　allowed　for　worms　to　cover
  up　the　stones　with　their　castings；　before　the　site　became　unfitted
  for　their　existence。　　Anyhow　the　contrast　between　the　state　of　the
  now　miscalled　〃stony　field；〃　well　stocked　with　worms；　and　the
  present　state　of　the　ground　beneath　the　old　beech…trees　in　Knole
  Park；　where　worms　appeared　to　be　absent；　was　striking。
  A　narrow　path　running　across　part　of　my　lawn　was　paved　in　1843　with
  small　flagstones；　set　edgeways；　but　worms　threw　up　many　castings
  and　weeds　grew　thickly　between　them。　　During　several　years　the　path
  was　weeded　and　swept；　but　ultimately　the　weeds　and　worms　prevailed；
  and　the　gardener　ceased　to　sweep；　merely　mowing　off　the　weeds；　as
  often　as　the　lawn　was　mowed。　　The　path　soon　became　almost　covered
  up；　and　after　several　years　no　trace　of　it　was　left。　　On　removing；
  in　1877；　the　thin　overlying　layer　of　turf；　the　small　flag…stones；
  all　in　their　proper　places；　were　found　covered　by　an　inch　of　fine
  mould。
  Two　recently　published　accounts　of　substances　strewed　on　the
  surface　of　pasture…land；　having　become　buried　through　the　action　of
  worms；　may　be　here　noticed。　　The　Rev。　H。　C。　Key　had　a　ditch　cut　in
  a　field；　over　which　coal…ashes　had　been　spread；　as　it　was　believed；
  eighteen　years　before；　and　on　the　clean…cut　perpendicular　sides　of
  the　ditch；　at　a　depth　of　at　least　seven　inches；　there　could　be
  seen；　for　a　length　of　60　yards；　〃a　distinct；　very　even；　narrow　line
  of　coal…ashes；　mixed　with　small　coal；　perfectly　parallel　with　the
  top…sward。〃　｛45｝　　This　parallelism　and　the　length　of　the　section
  give　interest　to　the　case。　　Secondly；　Mr。　Dancer　states　｛46｝　that
  crushed　bones　had　been　thickly　strewed　over　a　field；　and　〃some
  years　afterwards〃　these　were　found　〃several　inches　below　the
  surface；　at　a　uniform　depth。〃
  The　Rev。　Mr。　Zincke　informs　me　that　he　has　lately　had　an　orchard
  dug　to　the　unusual　depth　of　4　feet。　　The　upper　18　inches　consisted
  of　dark…coloured　vegetable　mould；　and　the　next　18　inches　of　sandy
  loam；　containing　in　the　lower　part　many　rolled　pieces　of　sandstone；
  with　some　bits　of　brick　and　tile；　probably　of　Roman　origin；　as
  remains　of　this　period　have　been　found　close　by。　　The　sandy　loam
  rested　on　an　indurated　ferruginous　pan　of　yellow　clay；　on　the
  surface　of　which　two　perfect　celts　were　found。　　If；　as　seems
  probable；　the　celts　were　originally　left　on　the　surface　of　the
  land；　they　have　since　been　covered　up　with　earth　3　feet　in
  thickness；　all　of　which　has　probably　passed　through　the　bodies　of
  worms；　excepting　the　stones　which　may　have　been　scattered　on　the
  surface　at　different　times；　together　with　manure　or　by　other　means。
  It　is　difficult　otherwise　to　understand　the　source　of　the　18　inches
  of　sandy　loam；　which　differed　from　the　overlying　dark　vegetable
  mould；　after　both　had　been　burnt；　only　in　being　of　a　brighter　red
  colour；　and　in　not　being　quite　so　fine…grained。　　But　on　this　view
  we　must　suppose　that　the　carbon　in　vegetable　mould；　when　it　lies　at
  some　little　depth　beneath　the　surface　and　does　not　continually
  receive　decaying　vegetable　matter　from　above；　loses　its　dark　colour
  in　the　course　of　centuries；　but　whether　this　is　probable　I　do　not
  know。
  Worms　appear　to　act　in　the　same　manner　in　New　Zealand　as　in　Europe；
  for　Professor　J。　von　Haast　has　described　｛47｝　a　section　near　the
  coast；　consisting　of　mica…schist；　〃covered　by　5　or　6　feet　of　loess；
  above　which　about　12　inches　of　vegetable　soil　had　accumulated。〃
  Between　the　loess　and　the　mould　there　was　a　layer　from　3　to　6
  inches　in　thickness；　consisting　of　〃cores；　implements；　flakes；　and
  chips；　all　manufactured　from　hard　basaltic　rock。〃　　It　is　therefore
  probable　that　the　aborigines；　at　some　former　period；　had　left　these
  objects　on　the　surface；　and　that　they　had　afterwards　been　slowly
  covered　up　by　the　castings　of　worms。
  Farmers　in　England　are　well　aware　that　objects　of　all　kinds；　left
  on　the　surface　of　pasture…land；　after　a　time　disappear；　or；　as　they
  say；　work　themselves　downwards。　　How　powdered　lime；　cinders；　and
  heavy　stones；　can　work　down；　and　at　the　same　rate；　through　the
  matted　roots　of　a　grass…covered　surface；　is　a　question　which　has
  probably　never　occurred　to　them。　｛48｝
  The　Sinking　of　great　Stones　through　the　Action　of　Worms。When　a
  stone　of　large　size　and　of　irregular　shape　is　left　on　the　surface
  of　the　ground；　it　rests；　of　course；　on　the　more　protuberant　parts；
  but　worms　soon　fill　up　with　their　castings　all　the　hollow　spaces　on
  the　lower　side；　for；　as　Hensen　remarks；　they　like　the　shelter　of
  stones。　　As　soon　as　the　hollows　are　filled　up；　the　worms　eject　the
  earth　which　they　have　swallowed　beyond　the　circumference　of　the
  stones；　and　thus　the　surface　of　the　ground　is　raised　all　round　the
  stone。　　As　the　burrows　excavated　directly　beneath　the　stone　after　a
  time　collapse；　the　stone　sinks　a　little。　｛49｝　　Hence　it　is；　that
  boulders　which　at　some　ancient　period　have　rolled　down　from　a　rocky
  mountain　or　cliff　on　to　a　meadow　at　its　base；　are　always　somewhat
  imbedded　in　the　soil；　and；　when　removed；　leave　an　exact　impression
  of　their　lower　surfaces　in　the　underlying　fine　mould。　　If；　however；
  a　boulder　is　of　such　huge　dimensions；　that　the　earth　beneath　is
  kept　dry；　such　earth　will　not　be　inhabited　by　worms；　and　the
  boulder　will　not　sink　into　the　ground。
  A　lime…kiln　formerly　stood　in　a　grass…field　near　Leith　Hill　Place
  in　Surrey；　and　was　pulled　down　35　years　before　my　visit；　all　the
  loose　rubbish　had　been　carted　away；　excepting　three　large　stones　of
  quartzose　sandstone；　which　it　was　thought　might　hereafter　be　of
  some　use。　　An　old　workman　remembered　that　they　had　been　left　on　a
  bare　surface　of　broken　bricks　and　mortar；　close　to　the　foundations
  of　the　kiln；　but　the　whole　surrounding　surface　is　now　covered　with
  turf　and　mould。　　The　two　largest　of　these　stones　had　never　since
  been　moved；　nor　could　this　easily　have　been　done；　as；　when　I　had
  them　removed；　it　was　the　work　of　two　men　with　levers。　　One　of　these
  stones；　and　not　the　largest；　was　64　inches　long；　17　inches　broad；
  and　from　9　to　10　inches　in　thickness。　　Its　lower　surface　was
  somewhat　protuberant　in　the　middle；　and　this　part　still　rested　on
  broken　bricks　and　mortar；　showing　the　truth　of　the　old　workman's
  account。　　Beneath　the　brick　rubbish　the　natural　sandy　soil；　full　of
  fragments　of　sandstone　was　found；　and　this　could　have　yielded　very
  little；　if　at　all；　to　the　weight　of　the　stone；　as　might　have　been
  expected　if　the　sub…soil　had　been　clay。　　The　surface　of　the　field；
  for　a　distance　of　about　9　inches　round　the　stone；　gradually　sloped
  up　to　it；　and　close　to　the　stone　stood　in　most　places　about　4
  inches　above　the　surrounding　ground。　　The　base　of　the　stone　was
  buried　from　1　to　2　inches　beneath　the　general　level；　and　the　upper
  surface　projected　about　8　inches　above　this　level；　or　about　4
  inches　above　the　sloping　border　of　turf。　　After　the　removal　of　the
  stone　it　became　evident　that　one　of　its　pointed　ends　must　at　first
  have　stood　clear　above　the　ground　by　some　inches；　but　its　upper
  surface　was　now　on　a　level　with　the　surrounding　turf。　　When　the
  stone　was　removed；　an　exact　cast　of　its　lower　side；　forming　a
  shallow　crateriform　hollow；　was　left；　the　inner　surface　of　which
  consisted　of　fine　black　mould；　excepting　where　the　more　protuberant
  parts　rested　on　the　brick…rubbish。　　A　transverse　section　of　this
  stone；　together　with　its　bed；　drawn　from　measurements　made　after　it
  had　been　displaced；　is　here　given　on　a　scale　of　0。5　inch　to　a　foot
  （Fig。　6）。　　The　turf…covered　border　which　sloped　up　to　the　stone；
  consisted　of　fine　vegetable　mould；　in　one　part　7　inches　in
  thickness。　　This　evidently　consisted　of　worm…castings；　several　of
  which　had　been　recently　ejected。　　The　whole　stone　had　sunk　in　the
  thirty…five　years；　as　far　as　I　could　judge；　about　1。5　inch；　and
  this　must　have　been　due　to　the　brick…rubbish　beneath　the　more
  protuberant　parts　having　been　undermined　by　worms。　　At　this　rate
  the　upper　surface　of　the　stone；　if　it　had　been　left　undisturbed；
  would　have　sunk　to　the　general　level　of　the　field　in　247　years；　but
  before　this　could　have　occurred；　some　earth　would