PIEDMONT  PLATEAU  AND  PORTIONS  OF  THE  APPALACHIANS.       7 13 
25  Firsl  report  of  the  State  agricultural  chemist  of  Maryland,  by  Philip  T. 
Tyson.    Annapolis,  1860,  pp.  1  15  ;_<>,  with  a  map. 
26  The  gabbros  and  associated  hornblende  rocks  occurring  in  the  neighborhood 
of  Baltimore,  Md.,  by  George  II.  Williams.  Bull.  U.  S.  Geol.  Survey  No.  28, 
pp.  78,  pis.  4. 
27  The  petrography  and  structure  of  the  Piedmonl  Plateau  in  Maryland,  by 
George  Huntington  Williams;  with  a  supplement  <>n  a  geological  section  across 
the  Piedmont  Plateau  in  Maryland,  by  Charles  R.  Keyes.  Bull.  Geol.  Soc.  Amer- 
ica, vol.  2,  1891,  pp.  301-322. 
2sThe  geologic  structure  of  the  Blue  Ridge  in  Maryland  and  Virginia,  by  Ar- 
thur Keith.    Am.  Geologist,  vol.  10,  1892,  pp.  362  368. 
29  The  volcanic  rocks  of  South  Mountain,  in  Pennsylvania  and  Maryland,  by 
George  H.  Williams.    Am.  Jour.  Sci.,  3d  ser.,  vol.  44,  1892,  pp.  482-496. 
30  Notes  on  the  Cambrian  rocks  of  Pennsylvania  and  Maryland,  from  the  Sus- 
quehanna to  the  Potomac,  by  Charles  D.  Walcott.     Idem,  pp.  -K'>!>^±82. 
31  Fossils  in  the  "Archean"  rocks  of  central  Piedmont  Virginia,  by  X.  H. 
Dart  on.     Idem,  pp.  50-52. 
82  Geology  and  physical  features  of  Maryland,  by  G.  II.  Williams  and  Wm.  B. 
Clark.  Extract  from  World's  Fair  Book  on  Maryland,  Baltimore,  1S9M,  pp.  1-07, 
with  map. 
33  Some  Maryland  granites  and  their  origin,  by  C.  It.  Keyes.  Bull.  Geol.  Soc. 
America,  vol.  4,  1893,  pp.  299-304. 
31  The  granites  of  Cecil  County,  in  northeastern  Maryland,  by  G.  P.  Grimsley. 
Jour.  Cincinnati  Soc.  Nat.  Hist.,  vol.  17,  1894,  pp.  59-07,  78-11  I. 
35  Description  of  the  Fredericksburg  sheet,' by  N.  H.  Darton.  Geologic  Atlas 
U.  S.,  folio  13,  U.  S.  Geol.  Survey,  1894. 
30  The  geology  of  the  Catoctin  belt,  by  Arthur  Keith.  Fourteenth  Ann.  Kept. 
U.  S.  Geol.  Survey,  pt.  2,  1894,  pp.  285-395;  Geologic  Atlas  U.  S.,  Harpers  Ferry 
folio  (No.  10),  TJ.  S.  Geol.  Survey,  1894. 
;7  Disintegration  of  the  granitic  rocks  of  the  District  of  Columbia,  by  (ieorge 
P.  Merrill.     Bull.  Geol.  Soc.  America,  vol.  G,  1895,  pp.  321-332,  pi.  xvi. 
38  Origin  and  relations  of  central  Maryland  granites,  by  C.  B.  Keyes.  with  an 
introduction  on  the  general  relations  of  the  granitic  rocks  in  the  middle  Atlantic 
Piedmont  Plateau,  by  G.  II.  Williams.  Fifteenth  Ann.  Kept.  P.  S.  Geol.  Survey. 
1895,  pp.  685-740,  pis.  xxxvi-xi.viii. 
89  Genera]  relations  of  the  granitic  rocks  in  the  middle  Atlantic  Piedmont 
Plateau,  by  G.  II.  Williams.  Introduction  to  origin  and  relations  of  central 
Maryland  granites,  by  C.  R.  Keyes.     Idem,  pp.  ('».'»'.»  684,  pis.  xxvn-xxxv. 
40  The  physical  features  of  Maryland,  including  the  physiography,  geology,  and 
mineral  resources,  by  Wm.  B.  (Mark.  Maryland  Geol.  Survey,  preliminary  publi- 
cation of  vol.  I,  pt.  :>,  PS97,  pp.  95,  with  ma]). 
"Outline  of  present  knowledge  of  the  physical  features  of  Maryland,  em- 
bracing an  account  of  the  physiography,  geology,  and  mineral  resources,  by 
Wm.  B.  (Mark.  .Maryland  Geol.  Survey,  vol.  1,  1897,  pp.  IMP  L'js.  Historical 
sketch.      Idem,   pp.  43    IMS,   with   map. 
"Geology  of  the  Piedmont  Plateau  area  of  the  Washington  quadrangle,  by 
Arthur  Keith.     Geologic  Alias  P.  s..  folio  To,  P.  s.  Geol.  Survey,  1901,  pp.  2  3. 
"The  structure  of  the  Piedmont  Plateau  as  shown  in  Maryland,  by  Edward 
B.  Mathews.     Am.  Jour.  Sci.,  4th  ser..  \«.l.  17,  L904,  pp.   1  M    L59. 
44 The  formations  and  structure  of  the  Piedmont  in  Maryland  correlated  with 
those  in  Pennsylvania,  by  Edward  P.  Mathews.  Bull.  Geol.  Soc.  America,  vol. 
1G,  1905,  pp.  329-346. 
""Report  on  the  physical  features  of  .Maryland,  by  William  Bullock  (Mark 
and  Edward  P.  Mathews.  Maryland  Geol.  Survey,  vol.  6,  L906,  pp.  27  261,  with 
geological  map. 
