68 "HE HAWKESBURY SANDSTONE. 
quantity of sand conveyed by it. A slight steady breeze blowing 
for aday in one direction would tend to carry a good deal of sand, 
which as it heaped up in the places where it was deposited would 
slip down to the angle of repose just as we see happening in al 
hour-glass. But if the sand were very equally distributed by a 
strong wind which tended to smooth down rather than to accumtt 
late heaps, then the angles of repose might be very low. I regard 
the laming as the result of periods of rest in the sand-drifts, and 
the thickness and direction as indications either of the duration 
or quarter of the wind. 
Since my attention has been directed to this I have carefull 
examined every sand-heap that came under my observation, and 
also noted the effect of the wind upon them. I had good 
opportunity for this at several of the coral islands inside the 
ier Most of them are formed of a fine-grained cal 
careous sandstone, partly cemented by the water and partly drifted 
by the wind. At Low Island I remained a week, and on™} 
arrival noted the height and dimensions of a small heap of sand 
which was forming under the shelter of some drift-wood. By 
planting sticks at various places in the heap I was able, not only 
to measure each day’s accumulation, but also the ts of & 
change of wind or a calm. It was at the end of the m 
ew hundred yards in superficial area, with a steep face te ex 
leeward side. There were two long tongues of sand on 
pie in the morning. The sandhill was only a few feet high 
a 
q 
i 
section through the day’s work the lamine were ig They : 
extremely thin, almost in fact like the leaves of & book. oe 
dipped in every direction and were inclined at various 05° ss 
coarser lamin 
they differed in the degrees of coarseness. 
strong 
The 
T have already observed, are not so much due to fe porticles ides 
breeze as to the faint ones, which carry away the parte J wis 2 
from a layer of sand, leaving the coarse 
r grains aod 
surprised ~ find in this small sandhill cage heavy eet a 
Sn eae Toon ee Ol ee 
; o o ! 
