﻿of 
  the 
  Northern 
  Appalachians. 
  

  

  427 
  

  

  on 
  the 
  terrace, 
  elevation 
  540 
  feet, 
  the 
  surface 
  was 
  found 
  

   to 
  be 
  covered 
  with 
  gravel 
  embedded 
  in 
  a 
  clayey 
  loam. 
  

   The 
  pebbles 
  were 
  of 
  white 
  quartz, 
  stained 
  yellowish 
  and 
  

   reddish, 
  and 
  of 
  all 
  sizes 
  up 
  to 
  a 
  maximum 
  of 
  3 
  inches. 
  

   Some 
  were 
  "beautifully 
  ellipsoidal 
  " 
  but 
  most, 
  although 
  

   showing 
  distinct 
  signs 
  of 
  water 
  wear, 
  were 
  subangular. 
  

   Many 
  pieces 
  had 
  one 
  rounded 
  side 
  and 
  many 
  of 
  the 
  

   larger 
  pebbles 
  were 
  broken, 
  from 
  which 
  it 
  was 
  concluded 
  

   that 
  the 
  disintegration 
  in 
  place 
  of 
  water-worn 
  gravel 
  had 
  

   given 
  rise 
  to 
  the 
  rough 
  angular 
  material. 
  

  

  From 
  an 
  inspection 
  of 
  the 
  Patuxent 
  formation 
  north- 
  

   oast 
  of 
  Baltimore 
  Professor 
  Barrell 
  concluded 
  that 
  the 
  

   gravel 
  beds 
  were 
  sufficient 
  to 
  supply 
  all 
  the 
  gravel 
  seen 
  

  

  Fig. 
  18. 
  

  

  Fig. 
  18. 
  — 
  The 
  Keisterstown 
  gravels. 
  

  

  in 
  the 
  "Lafayette" 
  near 
  Catonsville. 
  He 
  noted 
  that 
  

   the 
  formation 
  at 
  that 
  locality 
  was 
  practically 
  identical 
  

   with 
  the 
  Patuxent 
  north-east 
  of 
  Baltimore 
  and 
  ques- 
  

   tioned 
  whether 
  it 
  might 
  not 
  actually 
  be 
  the 
  latter 
  forma- 
  

   tion. 
  He 
  decided, 
  however, 
  that 
  this 
  was 
  probably 
  not 
  

   the 
  case 
  because 
  of 
  the 
  noticeable 
  concentration 
  of 
  gravel 
  

   at 
  and 
  near 
  the 
  surface, 
  which 
  he 
  ascribed 
  to 
  wave 
  work. 
  

   Professor 
  Barrell 
  was 
  especially 
  interested 
  in 
  the 
  evi- 
  

   dence 
  he 
  found 
  in 
  the 
  vicinity 
  of 
  Eeisterstown, 
  Md., 
  

   consisting 
  of 
  water-worn 
  pebbles 
  and 
  cobbles, 
  indicating 
  

   the 
  presence 
  of 
  gravels 
  on 
  the 
  730-745 
  foot 
  terrace. 
  He 
  

   considered 
  that 
  this 
  evidence 
  pointed 
  to 
  a 
  marine 
  origin 
  

  

  