Muhheakantuck and this Little Fifth Order Fresnel
This earth cache is available ONLY from a water vessel. A vessel
that displaces very little water is best used for this location.
The I.P. will bring you to the middle of the river where the Esopus
Meadows Lighthouse is located. DO NOT climb on the lighthouse base
or any part of the lighthouse property. It is private property,
patrolled by the sheriff’s department, the Coast Guard,
alarmed and monitored….soon to be a B&B but also open
for tours and learning.
History of the lighthouse…
The Esopus Meadows Lighthouse, fondly nicknamed the “Maid
of the Meadows”, was completed in 1871. It replaced an
earlier structure built in 1839 on land ceded to the United States
Government from the state of New York. A lighthouse was needed on
the Hudson River to warn mariners of the mud flats known as the
Esopus Meadows located off the western shore of the river.
According to the late Roy Black Bear, of Esopus, the word
"Esopus "means a "small stream or river," a name generated by the
Lenape tribe. The "meadows" in the lighthouse's name arose from the
expanse of grazing land that once existed between the Hudson's
current west shore and the lighthouse. It is now a flooded
flat.
There are two high and two low tides each day and the current on
the channel side of the lighthouse runs about two knots. One would
not notice that the flats run out in to the river if not for being
warned by the lighthouse.
The lighthouse was built on a new foundation, located to the
south of the former location, traces of which are still visible on
the adjoining small island. Two hundred and fifty piles, each 40
feet long, were driven into the river bottom. They were cut off
three feet below the mean water mark, capped with 12-inch square
timbers and topped with a deck of three-inch pine. Granite blocks
were stacked 16 feet high producing a pier with a diameter 49 feet
at the base and 46 feet at the top. On top of this pier was built a
wooden keeper’s dwelling with a mansard roof and clapboard
exterior. Inside the house are a kitchen, sitting room and
equipment room on the first floor and three bedrooms and a bath on
the second.
The light tower extends above the living quarters with an
octagonal deck housing the light. Situated 53 feet above the mean
water line, the lantern room contained an optic fifth-order Fresnel
lens providing a 270-degree arc of light that was visible for 12
nautical miles.
Tides and their effect on the river…
You may notice something strange, namely, that the water
sometimes moves up the river, and sometimes it moves down the
river. The Native Americans noticed this change too-their name for
the river, ‘Muhheakantuck’, means ‘water that
flows both ways’. This change happens not because of boats,
or freshwater coming into the river, or waves, although all of
these things can play a role. It happens because of the tides.
Tides are caused by the interaction between gravitational and
centrifugal forces, with the strongest tides resulting from the
pull of the moon. Water levels rise on the side of the earth
nearest the moon and on the side opposite the moon, causing a
‘bulge’ of water around the earth. The Hudson, like
most places on Earth, has two low and two high tides per day.
Although the gravitational pull of the moon is stronger than that
of the sun, the sun still plays a role in the behavior of tides on
Earth. When the sun and the moon are in line with one another (when
the moon is full or new), their gravitational pulls add together
and cause very strong tides, called spring tides. When the moon and
sun are at right angles to one another (during half moons), their
pulls partially cancel each other out, and a weak tide, or neap
tide, results. These cycles happen every 14 days.
Now, because the Hudson is open to the ocean, semidiurnal tides
travel up the Hudson all the way to the Troy dam. Tides make the
water in the Hudson slosh back and forth, much as you would see in
a bathtub. The river runs north for six hours and then runs south
for six hours. However, freshwater from rivers can change the flow
of the river and even prevent the tidal push during very heavy
runoff. The salt front, which is the leading edge of the diluted
sea water, is usually south of the Tappan Zee Bridge, but it often
comes to Poughkeepsie or even further, especially during
droughts.
The Hudson is also influenced by the interactions of fresh and
salt water, because salt water is heavier than fresh water.
Consequently, salt water flows upriver from the ocean along the
bottom of the river, while freshwater flows downriver over the top.
There is some mixing of the fresh and salt during spring tides or
high freshwater flows, but usually there is a layering effect of
fresh and salt water called ‘stratification’.
So, what does all this mean for the Hudson? Well, it means that
you get a mix of fresh and salt water in the river, but it depends
where you are, what the tides are doing, how deep you sample the
water, how strong the wind and rain effects are, etc. It also means
that you find a large variety of different animals and plants as
you move upriver from the mouth of the Hudson.
River definition: A river is a natural stream of water,
usually freshwater, flowing toward an ocean, a lake, or another
stream. In some cases a river flows into the ground or dries up
completely before reaching another body of water.
Estuary definition: An estuary is a semi-enclosed coastal
body of water with one or more rivers or streams flowing into it,
and with a free connection to the open sea.[1]Estuaries are often
associated with high levels of biological diversity.
Definitions taken from Wiki-pedia. Other information contributed
by:
www.esopuslighthouse.org
www.abouttown.us
www.ecostudies.org
To earn your smiley for this earth cache, please do and answer
the following:
- Post a photo of you in your watercraft next to the lighthouse.
Additional photos are appreciated but not necessary.
Send me an email with the answers to the following questions. Do
not post the answers in you log even if encrypted.
- List some reasons, natural or man-made, as to why the meadow
has turned in to a mud flat.
- Face the staircase one would walk up to get to the lighthouse.
Comparing the SW and SE corners, what are some reasons it looks the
way it does. Include at least one of your thoughts about the soil
composition that the piles were driven into that could cause what
has happened to the lighthouse base.
- Approximate the level of the river based upon how many
foundation blocks you can see. Assuming that high tide allows you
to see 4 rows and that low tide allows you to see 6 rows (equating
to an approximate 4’ tide variation) estimate the tide level
at the time of your visit. Was it low tide, high tide, or somewhere
in between?
- List some differences between a river and an estuary. At this
location, is the Hudson a river or an estuary?
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