Drumlin, smooth, half egg-shaped or ellipsoidal hill which formed
beneath Quaternary GLACIERS. Drumlins [Gaelic druim, "hill"] were
first described in Ireland. They lie parallel to the direction of
ice movement, the blunt (stoss) end facing up-glacier, the lee
sloping down-glacier. Drumlins may be up to 50 m high and several
kilometres long, with an average length/width ratio of 2 or 3 to 1.
Highly elongated drumlins are often called drumlinoids.
Drumlins may be composed of layers of till (sediment deposited
by a glacier), frequently clay-rich, in which the pebbles are
oriented subparallel to drumlin elongation and the direction of ice
flow, although many drumlins have cores of stratified sand,
boulders or bedrock. Rock drumlins are rock outcrops smoothed by
ice to a drumlin shape. Scientists are not certain how drumlins
originated.
The "dilatancy" theory postulates that drumlins were initiated
beneath ice of a critical thickness, down-glacier from high basal
pressure zones and up-glacier from moraine deposition, where till
expanded, forming hummocks.
Other hypotheses suggest that subglacial crevasses, frost heave,
helical ice motion or water loss from saturated till initiated
hummocks.
Drumlins with a core of stratified sediments are glaciofluvial
in origin, formed by deposition in cavities which were cut in the
base of the ice by a large discharge of subglacial melt water.
All theories hold that the hummocks were subsequently enlarged
by layers of till which were plastered on and streamlined by the
ice sliding over.
To claim
the earthcache you must send me the answers to these 4
questions.
Question #1 What is the length in meters or feet from the posted
cords (top) to the base of the slope?
Question #2 When was the Mount Uniacke house built?
Question #3 How large in hectares is the estate now?
Question #4 what two main bulidings where at the estate in the
1800's that aren't there now?
Please take a picture of you or gps with house in the background
to prove you where there.
You do not
need to wait for confirmiation from me before posting online.
However, any logs that do not fulfill ALL requirements will be
deleted.