ON THE GOTHAM MARBLE 
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but elongated and interlacing ridges, and that the “ trees ” 
rose into, not between them. 
Doubtless some recrystallization of the silt into “ atmo- 
sphere ” went on long afterwards, and both exaggerated 
the hummocky surface and occasionally fractured the 
“ canopy,” which is not uncommon. 
A few objections may here be noticed. 
(i) Why when the precipitate was scanty did it soak to 
the bottom of the silt, but when abundant deposit on the 
top ? Firstly, because in the “ summer ” the silt was 
much firmer. Secondly, because it is well known to chemists 
that rapid crystallization from solution leads to many small 
crystals, but if slow, like seeks like, and all is deposited on 
one or two large crystals. When the precipitate is abundant 
it will set anywhere ; when scanty, it seeks its like. 
(ii) Why do all the “ trees ” reach the bottom ? Because, 
even if all the cracks did not, a line of percolation once taken 
up would be permanent. 
(iii) Do all the “ trees ” rise to the top ? Yes, if dissected 
back. High “ hedges ” and “ branches ” do not. 
IV. Detailed Account of the Origin of Peculiar Forms of' 
Gotham Marble. 
(i) End-Cothams. These exist, or in other words the 
Landscape Marble is patchy in distribution, because in all 
but the stillest water the precipitate was washed away* 
They are always coarse and shelly because they were laid 
down in slightly rougher water than the more central parts* 
They contain slabs of False Gotham Marble, because that 
is a rougher water deposit. They slope off at an angle 
because the uppers contracted in taking their final form, 
whilst the basement beds were already set. 
(ii) The Simple Horizontally Banded Form probably 
M 
