The GreylocTc Synclinoriitm. — Dale. 5 
Traversing the folds of this cauoe-like complex syuclinorium is 
a cleavage-foliation sometimes microscopicall}- minute, dipping 
almost uniformh' east. This cleavage-foliation is generally dis- 
tinct from the " slaty cleavage " earl}' described b}' Sedgwick, 
Sharpe, and Sorby, and reproduced experimentally by Tyndall and 
Jannettaz ; but consists sometimes of a minute joint-like fracturing 
of the laminae, but more generally of a faulting of the lamiuse as 
the result of their extreme plication — a mode of cleavage (aus- 
weichungs-clivage) so well described by Heim,* and recentl}- re- 
produced in part b}' Cadell t b}' a slight modification of the exper- 
iments made b}' Alphonse Favre of Geneva in 1878. + This fault- 
cleavage, when carried to its extreme, results in a form of cleavage 
xery nearly approaching, although not identical with ' ' slat}' clea- 
vage. " To the unaided eye all traces of stratification-foliation are 
lost and even under the microscope they are so nearly lost as to be 
of little or no avail in determining the direction of the dip. I 
Liihological Stratigraphy. There are five more or less distinct 
horizons in the Greylock mass. Beginning above: The Greylock 
Schists: muscovite (sericite) chlorite and quartz schist, with or 
without biotite, albite, octahedral magnetite, tabular crystals of 
interleaved ilmenite and chlorite, ottrelite, microscopic rutile and 
tourmaline. Thickness 1200 to 2000 feet. Part of Emmons' Pre- 
Cambrian or Lower Taconic No. 3, " Talcose Slate." Walcott's 
Hudson River (Lower Silurian). 
The Bellows Pipe Limestone, (so named from its occurrence at the 
"Bellows Pipe " in the notch between Ragged Mt. and Greylock): 
Limestone more or less crystalline, generally micaceous or pyri- 
tiferous, passing into a calcareous mica schist or a feldspathic 
quartzite or a fine grained gneiss with plagioclase and occasional 
*A. Heim. Mechanismus der Gebirgs bildung, Im Anschluss an die 
Geologische Monographic der Toedi-Windg«llen Gruppe. Basel 
1878. 
fHenry M. Cadell. Experimental Researches on Mountain Building. 
Paper read before the Royal Society of Edinb., Feb. 20, 1888. 
Transac. Roy. Soc. Edinb. Vol. XXXV, part 7, p. 337, 3.57. Ab- 
stract in Nature, Vol. 37, p. 488, Mch. 23, 1888. Third series of 
experiments. 
tAlphonse Favre. The formation of Mountains. Nature, Vol. XIX, 
1878, p. 103. 
gSlaty cleavage results from the destruction of the small laminie by 
the breaking up of the sedimentary arrangement of the particles and 
changing the direction of the axes of all the particles. In this connec- 
tion see: Alfred Harker. The causes of Slaty Cleavage: compression v. 
shearing. Geological Magazine, London, 188.5, p. 15. and also by the 
same author; On the Successive Stages of Slaty Cleavage. Ihhl, p. 266. 
