Quick description: Rising
up to 627 feet above mean sea level, West Rock Ridge is one of the
most prominent features of the New Haven region. West Rock affords
the visitor a spectacular view; it is estimated that one can see
approximately 200 square miles from various locations on the ridge
with excellent views of New Haven Harbor and Long Island Sound.
West Rock Ridge is composed of igneous rock that formed when magma
intruded into sedimentary rocks and cooled. These rocks formed
between 220-200 million years ago during the late Triassic and
early Jurassic periods of geologic time. More recently, during the
last Ice Age (about 20,000 years ago), glacial ice about 1 mile
thick scraped across West Rock. The ice created parallel grooves
(glacial striations) on the rock. When the ice melted it deposited
unsorted glacial debris (glacial till) and large boulders
(erratics) on top of the rock.
Location: West Rock Ridge State Park, Hamden CT
N41o19.940, W072o57.677
Date Listed:
Waymark Code:
Listed by: CTGEOSURVEY
Purpose: This EarthCache is published by the Connecticut
Geological and Natural History Survey of the Department of
Environmental Protection. It is one in a series of EarthCache sites
designed to promote an understanding of the geological and
biological wealth of the State of Connecticut.
Supplies: You will need a copy of this login to answer
the questions once on site. You will also need to take a few photos
on site. Spoilers may be included in the descriptions or links.
Directions:Off the Merritt Parkway (Route 15): take Exit
60. Turn right off the exit ramp onto Dixwell Avenue/Route 10
South. Take a right at the next light onto Benham Street. Follow
Benham Street to the end. Turn left onto Main Street. At a sharp
left, turn right into the parking lot for the Lake Wintergreen
area.
For main entrance: continue down Main Street to the end. Take a
right onto Wintergreen Avenue. Go under the parkway. The main park
entrance will be on the right. If the gate is closed (see "Hours"
information), park at West Rock Nature Center across the
street.
Hours:
The park is open for walk-in access from 8 am to sunset.The
south overlook drive to the summit is open for vehicles Thursday
through Sunday from Memorial Day through the last weekend in
October
Introduction. The geology of West Rock Ridge State Park
is very similar to the Geology of Sleeping Giant. As an
introduction to this EarthCache, the interested cacher may read the
introduction to 'The Giant Sleeps Today' EarthCache. A more
detailed (technical) geologic story for both parks have been
written and are available on the Connecituct DEP web-site under
'Geology of State Parks'.
ACTIVITY 1. Find the above location (N41o19.940,
W072o57.677) and park your car if you are in one. The
view you will get at this location is fantastic. One can see north
past the Sleeping Giant to Meriden Mountain and Lamentation
Mountain, 20-25 miles away. 
To the east is East Rock and to the south, one
can see Long Island on a clear day. The view easily spans 50 or
more miles. The farthest parts of Long Island are about 35 miles
distant. Of course, the city of New Haven is laid out below.
Southern Connecticut State University is prominent to the
east-northeast, New Haven Harbor to the southeast, and the Yale
Bowl may be picked out to the southwest. The hills to the west are
underlain by Paleozoic metamorphic rocks. Triassic sedimentary
rocks underlie the valley. A geologic unconformity, which is
exposed behind a nearby shopping center, separates them. The hills
that form the skyline to the east are underlain by the up-tilted
edges of the Jurassic lava flows. The lowland between is underlain
by Triassic New Haven Arkose.
Question #1. Look carefully at the gross morphology of this
site. Cliffs are prominent on the west, having a height of 100 or
more feet. To the east, the rock forms a rather planar ramp-like
surface that tilts downward. There is a geologic reason for this.
Explain in one sentence why this is so. (Hint: The answer to this
question may be found in the last paragraph of the introduction in
the Sleeping Giant EarthCache.)
Either walk or drive your car to N 41o20.313, W
072o57.985. If you hike, you may take the blue-trail or
just follow the road north. Along the way note the cliffs to the
west and the view from the cliffs. You may be able to see the
Wilber Cross Parkway.
ACTIVITY 2. Judges Cave formed at the base of several a large
stones that lie on top of the bedrock (ledge). The cave is formed
by three or four stones that look like they could be fit together
to form a larger stone, i.e., they are fragments of a once larger
stone. Indeed, that appears to be the case. A large stone and a
couple of companions were deposited from glacial ice after they
were entrained frozen within a glacier to the north, maybe as far a
Meriden Mountain. The glacier came over this ridge and upon melting
deposited this rock. During the deposition, or shortly thereafter,
the largest stone broke along preexisting joints into three or four
fragments and slid slightly away from each other, leaving shelters
in between. What is geologic term for these large boulders. Hint:
the answer can be found in this cache description and in Michael
Bell's delightful book, The Face of Connecticut on p. 123,
or in Flints (1965) description of the glacial geology of this
area.
If you wish, scout out the area. Flint (1965) describes a long
glacial striation in the vicinity of Judges Cave that I missed
during my reconnaissance. For extra credit, see if you can find and
photograph the striation.
Additional information and references:
Bell, Michael, 1985, The Face of Connecticut: Hartford,
Connecticut Geological and Natural History Survey, Bull. 110, 196
p.
Flint, R.F., 1965, The surficial geology of the New Haven and
Woodmont Quadrangles. Geological and Natural History Survey, Quad.
Rept. 18, 42p
Steinen, R.P., 2006, Geology of West Rock Ridge State Park:
in Geology of State Parks,
DEP website.
Steinen, R.P., and Dwyer, A., 2006, Geology of Sleeping Giant
State Park, in Geology of
State Parks, DEP website.
How do people log this EarthCache? People should try to
answer the two EarthCache activity questions and send an image of
themselves at the top of West Rock with the City of New Haven
behind.
Difficulty: 2
Terrain: 1: site may be accessed by automobile. A short
hike of less than 0.5 mi (one way) is over mostly level ground.
Type of land: State Park
EarthCache category: Igneous intrusion; glacial
feature