MR.  HOENEE  ON  THE  ALLUVIAL  LAND  OE  EGYPT. 
73 
ffoiv  far  a local  secular  rate  of  increase  of  the  alluvial  land  may.,  with  'prohahility, 
he  estimated  from  these  recent  researches. 
The  Obelisk  at  Heliopolis  and  the  colossal  statue  of  Ramesses  II.  on  the  site  of  Mem- 
phis, are  the  only  monuments  of  high  antiquity,  and  of  a known  age,  upon  and  around 
which  the  sediment  of  the  inundations  has  accumulated,  in  that  part  of  Lower  Egypt 
where  alone  it  was  practicable  to  undertake  the  researches  described  in  this  memoir, 
viz.  in  the  vicinity  of  Cairo. 
In  the  excavations  made  around  the  Obelisk  of  Hehopohs,  it  was  found  in  that  nearest 
to  it  (A)*  that  the  sm’face  of  the  pedestal  on  which  the  obelisk  stands  was  reached  at 
a depth  of  5 feet  6 inches,  and  that  the  pedestal  measured  6 feet  10^  inches  in  height, 
making  together  12  feet  4^  inches  from  the  surface  of  the  ground  to  the  foot  of  the 
pedestal.  But  we  may  presume  that  the  pedestal,  at  the  time  of  its  erection,  would  be 
sunk  somewhat  below  the  then  surface  of  the  ground,  and  if  we  allow  for  that  1 foot  4-| 
inches,  we  have  an  accumulation  of  sediment  of  11  feet  from  the  present  surface  of  the 
ground  to  the  level  where  the  pedestal  first  appeared  above  the  surface,  at  the  time  of 
the  erection  of  the  obelisk. 
The  obelisk  is  believed  to  have  been  erected  2300  years  B.c.f,  and  adding  1850,  the 
year  when  the  observation  was  made  (June  1851,  i.  e.  before  the  inundation  of  that 
year),  we  have  4150  years  in  which  the  11  feet  of  sediment  were  deposited,  which  is  at 
the  rate  of  3T8  inches  m a century. 
But  entire  reliance  cannot  be  placed  on  this  conclusion ; and  this  very  ancient  monu- 
ment of  known  age,  apparently  so  well  calculated  to  solve  the  problem,  from  unforeseen 
circumstances  in  the  nature  of  the  ground  on  which  it  was  erected,  has  failed  to  afibrd 
the  true  chronometric  scale  which  it  was  hoped  it  would  have  done.  For  there  is  great 
uncertainty  whether  the  9 inches  of  “disturbed  ground”  is  entirely  true  sediment,  and 
also  whether  the  sand  that  was  reached  before  coming  to  the  base  of  the  pedestal  was 
deposited  by  the  Nile,  or  was  original  desert  ground,  that  had  been  sunk  into  for  the 
foundation.  I have  already  stated  J that  the  appearances  round  the  obelisk  render  it 
probable  that  the  site  originally  chosen  for  the  temple  and  city  of  Heliopolis  was  a por- 
tion of  land  somewhat  raised  above  the  level  of  the  rest  of  the  skirt  of  the  desert,  and 
advancing  into  the  low  grounds  then  inundated  by  the  Nile.  This  view  is  supported 
by  the  differences  in  the  nature  of  the  soils  passed  through  in  the  excavations  to  the 
west  of  the  obelisk,  that  is,  nearer  to  the  Nile,  from  those  to  the  east  of  it,  especially 
the  excavation  H,  which  was  due  east,  and  therefore  on  the  supposed  offshoot  from  the 
desert  land.  Thus, 
In  the  excavation  B,  100  yards  west  of  the  obelisk,  there  was  found  13  feet  3 inches 
of  mud  (argillaceous  sediment);  in  C,  784  west,  14  feet  3 inches  of  mud,  which  in 
neither  pit  was  gone  through,  as  the  filtration  water  prevented  further  progress. 
In  the  excavation  D,  270  yards  south-east,  there  was  found  12  feet  5 inches  of  mud, 
* These  excavations  are  described  in  Part  I.  of  this  Memoir,  from  page  IBl  to  136. 
t Id.  page  123.  J Id.  page  123. 
