Isostatic Rebound in Lower James Bay in the Past 400
Years and Locating Thomas James’ and Henry Hudson’s

By Leslie Trager
2500 Virginia Ave., NW.
Washington, DC, 20037
202 735 5112

Using historical data for lower James Bay, Canada and satellite maps made
with radar from Geomapapp (developed by Lamont-Doherty Earth
Observatory Columbia University, version 2.8), it can be definitively shown
that uplift from isostatic rebound in lower James Bay during the past
approximately 400 years has been five meters. This was based on an
analysis of the shore of Charlton Island as described by Thomas James for
the years 1631-1632 published on his return under the title, “The Strange and
Dangerous Voyage of Captaine Thomas James, 1633” and Henry Hudson’s
campsite in the winter of 1610-1611 as described by Abacuk Prickett in his
memoire of 1625. Both of these describe a landscape that is only compatible
with the land as it exists today at five meters above mean sea level.
1 This
study also allows us to locate the sites where Thomas James and Henry
Hudson made their winter camps, neither of which has been found.

It is well known that the area of Hudson Bay - James Bay has seen significant
uplift due to isostatic rebound since the melting of the glacier about 12,000
years ago. Raised beaches can be found in some areas at 500 feet above
present sea level. Until the advent of GPS, determining the rate of rise was
done by finding a shell or other formerly living substance on a raised beach
and determining its age through radiocarbon testing. This resulted in
estimating the uplift rate for lower James Bay at 6.6mm per year or .66
meters over 100 years. [See republication of data at p. 789,
Mitrovica, 2000].
Such data was known to be inaccurate due to such problems as old shells and
old water affecting the dates derived from radiocarbon testing. [
Rick, 2005];
Website, Beta Analytic Europe.

GPS data shows that today lower James Bay is rising at the rate of 10mm per
year or 1 meter per 100 years. [
Sella, 2006]. But, it does not necessarily mean
that the rate has been uniform even within relatively recent times.
Observations made at Churchill on Hudson Bay between 1940 and 1992
showed that during the period 1940 to 1975 the rate of uplift was 4.4 mm per
year, while the rate from 1977 to 1991 was more than double - 9.4 mm per
year. [
Gough, 2000].

A comparison of the topography of today with that described by two, well-
known explorers 400 years ago, shows that over the past 400 years, the uplift
has been 5 meters or 12.5 mm per year, which is slightly faster than the
present rate shown by GPS. The two locations described are Thomas James’
winter camp of 1631-32 on Charlton Island located in lower James Bay and
Henry Hudson’s Camp for the winter of 1611-12,approximately 30 miles east
of Charlton Island at the entrance to Rupert Bay (
Map 1). The topographic fit
between the descriptions of these unique locations and today’s 5 meter level
is such that it seems fairly certain that the location for these two places has
been determined.

James’ Winter Camp Location on Charlton Island:
Description by Thomas James of Charlton Island
The explorer Thomas James in 1631 looked for a place in southern James Bay
to winter over. He ended up at an island which he named Charlton Island.
Because he kept a diary, which he later published under the title of “The
Strange and Dangerous Voyage of Thomas James,” we know what he
observed. From this diary we know that the houses built for the winter were
located at 52 degrees, 3 minutes N, that a spring was 3/4 miles away from
these houses, that beyond this spring was an inner harbor which his ship
could not enter because of insufficient water at the entrance, that his ship was
anchored (and sunk for the winter) in front of these houses and that these
houses were located near the beach on the south side of a protective bluff.
Thus, James gives us the following descriptive clues:

On October 3, 1631, when he landed on the island for the first time, he wrote:

“[B]ut that that did reioyce me most, was, that I did see an opening into the Land, as if it
had been a river. To it we make with all speede, but found it to be barr’d; and not 2 foote
water at full sea on the Barre: and yet within, a most excellent fine Harbour, having 4
fathoms water.” [Spelling in original.]

On that first day James also discovered a spring for on December 23, James

“When I landed first upon this Iland, I found a spring under a hilside: which I then
observing, had caused some trees to be cut for markes to know the place againe by. It
was about three quarters of a mile from our house.”

He used that spring as a source for water during the winter, so we know that
the spring was on the same side of this blocked harbor, as he would not have
been able to safely cross the harbor to get to the spring, particularly before
and after freeze up.

The houses he built were near the beach and were sheltered from the north
wind by a bluff or hill. At page 53 under October 26, he wrote that the houses
were “under a south bank which did shelter us.” I believe that he means that
the houses were south of the bank, as any other interpretation is inconsistent
with his described location in the bay at Charlton Island. When they got the
goods off the ship, and hauled up the long boat, they “went along the breach
[beach] side in the dark towards the house.” (p. 54). The houses are described
as in the woods on sandy ground. This would indicate that the houses were
fairly close to the beach and not too far up any hill or ridge.

Near the end of his stay, James determined the latitude for these houses
(after having “practiced [with the instruments a] fortnight”) to be “in 52
degrees, and 3 minutes.” (Entry for June 13, 1632). This latitude was
confirmed by archaeologist W.A. Kenyon in his monograph “The Strange and
Dangerous Voyage of Captain Thomas James,” Toronto, The Royal Ontario
Museum, 1975, p. 8 (James “located his wintering place on Charlton Island at
52 03' north, which, for all practical purposes, is dead on”).

Map 2 showing Kenyon’s map with a dot for the location of James’
houses on today’s Charlton Island, called “Charlestown.”

Comparison of James’s description with the land at 5 and 6 meters.
Map 3
shows Charlton Island with a contour line at six meters. Point B is a
point located 52 degrees 3 minutes north, just above the point where the six
meter line crosses this latitude line and the location where James built his
2 Longitude for this location is about 79 degrees 17 minutes West.
Point C on this map shows a location 1.2 kilometers (3/4 of a mile) from the
houses, which would be the approximate location of the spring.
Point D on the map shows a possible inner harbor, which could have been
seen as an opening looking like a river.

Map 4 shows the profile of Point D. The white line on the map represents
the area profiled. As can be seen, this harbor is about half a kilometer wide. It
reaches a depth of 4 meters, which is approximately equivalent to the 4
fathoms found by James. Most importantly, there is a bar at the entrance to
the inner harbor which rises to about 5.5 meters. Again, this is consistent
with James’ finding of a good inner harbor with a bar at the entrance leaving
“not 2 foote water at full sea.” The tidal difference in this area is six feet or a
little less than two meters, so the mean tidal difference would be one meter.

Map 5 shows this same area of Charlton Island at the 5 meter level. Note
that at the 5 meter level, there is a thin bar across the mouth of the inner
harbor. As noted, the Map 4 profile showed the bar at the entrance to be
about 5.5 meters. Because the tide at Charlton Island is about six feet and
James said the water rose only two feet above the bar at high tide, we know
that this bar had to be two feet, or .6 meters below the high water mark. This
means that maximum sea level for this location would have been at what is
today approximately the six meter contour (5.5 meters plus .6 meters equals
6.1 meters). Since the mean tidal difference in this area is one meter,
subtracting this one meter gives us the five meters above mean sea level for
this location.

James states that the ship had been moved close to shore and describes the
ship as being a “flight shot” from the houses. (p. 59).
Map 6 shows a profile
of the land from the estimated location of the houses (the flat area at the 7
meter line). At this point, the bay drops first to a level area at five meters and
then to a flat area at the three meter level. James' ship was 70 tons (James, p.
2) and, consistent with ships of that era, would have a draft of about seven
feet and another seven feet of freeboard for a total of about fourteen feet. The
second level would be sufficient to partially sink the ship. This area is located
approximately 0.3 km offshore. Since there is a six foot tidal difference in this
area, this area would be consistent with a location that James describes as the
place where the ship was brought and sunk for the winter, with the
expectation of raising her later.

James also described sending others on October 4, 1631, to look at another
nearby river as a possible wintering location. That would undoubtedly be the
river or bay at location E on Map 2. Beyond that, jutting out into the ocean is
the area later known as House Point. (See
Map 11 infra.)

Map 7 shows that the location of the houses at 52 3' latitude is in front of a
steep hill which is consistent with James’ description of the houses in front
of a “bank” sheltering them. (Map 7 has contour lines at 2 meter intervals,
starting at the six meter level). He also states that they had a watch tree
which they climbed which was at the highest point of the island. (p. 76).
Clearly, just behind the proposed location for the houses is the highest point
of the island. In fact, later, when leaving, they made a signal fire at the top of
the watch hill, which caused the trees to catch fire, and James describes
how he ran down a steep hill towards the houses. (June 25, p. 84). This
location is consistent with such a description.

Contour Lines below 5 meters are inconsistent with James’s
At the four meter level, the shape of the land changes drastically and assumes
an outline similar to the present.
Map 8 shows the 4 meter level. There is no
longer any inner harbor with a bar at the entrance. Nor is there any place to
bring a ship and anchor in front of the houses at 52 3'. There is an island at
the entrance to the harbor, but James made no mention of such an island
(and this island does not exist at the 5 meter level). The former inner harbor
is now just an unconnected depression (see circular figure just
past the head of the bay).
Map 9 shows the 3 meter level. The little circles in
the former bay area are all cut off from the sea and are too small to meet
James’ description of an inner harbor suitable for a ship except for the bar.
Map 10 shows the 2 meter level. Here, the bay described by James has
almost disappeared.

Maps Made for Hudson Bay Company.
As can be seen from the above maps showing Charlton Island as it exists
today, very little of the bay James described is left today. But historical maps
from the Hudson Bay Company show that even as late as 1804, Charlton
Island had a much larger bay in this area.
Map 11 is from 1804 - almost 200
years after James was there. At the base of “James Point” is an indentation in
the shore, which is consistent with the indentation shown in the same
location on Map 9 (the three meter map).

Proposed Inner Harbor still retains unique shape today.
Map 12
is a photo of what the proposed inner harbor looks like today from
the air.
4 Map 13 is this same area as shown by Google Earth. Both of these
photos show a pond with water flowing out of the pond. The shape of the
outlet of the pond is consistent with James’ description of what was then the
inner harbor - particularly the bar at the entrance. This bar has to be stone,
because if it had been a mere sandbar, the continued flow of water out of the
pond (as well as the earlier tidal action and waves) would have eroded any
sandbar and the pond would not exist today.

Hudson's Winter Camp of 1610-11.
Description of Hudson’s Camp.
The only description of Hudson’s wintering place of 1610-11 is found in the
writing of Abacuk Prickett, a member of the crew who returned without
Hudson and some of his men in 1611. Fourteen years later (1625) he
published his story of that voyage. He describes how, after cris-crossing
Hudson Bay (“having spent three moneths in a labyrinth without end”), at
the end of October, 1610, they went into what is today called James Bay. They
sailed south looking for a place to spend the winter and ended up in the
southwest corner of James Bay, today known as Hannah Bay. Finding no
suitable place to land, the ship went north. Prickett states that at some point
the ship turned and:

“Wee stood up to the east and raysed three hills, lying north and south: we went to the
furthermost, and left it to the north of us, and so into a bay, where we came to an
anchor. Here our master sent out our boat, with myselfe and the carpenter to seeke a
place to winter in.... [W]e went downe to the east, to the bottome of the bay; but
returned without speeding of that we went for. The next day we went to the south and
the south-west, and found a place, whereunto we broughtour ship, and haled her
aground: and this was the
first of November.” (Italics original.)5

In short, the ship had gone to the bottom of James Bay at the western
portion, and now was sailing north and then east. He describes the land
coming from west to east by saying that there were three hills running from
north to south. He next describes leaving the bottom hill to the north and
entering a bay. The bay he describes must have a top or head more or less
northward because he describes going east to the shore at the bottom
of the bay on the first day and then to the other side of the bay going south
and southwest.

A further clue to the location of this area is found in the “Naval Tracts” by
William Monson, written earlier, but published in Churchill’s Collection of
Voyages and Travels in 1744. This states that he received “from the mouth of
the master that came home from Hudson,” presumably Robert Bylot, that
“they wintered in an island in fifty-two degrees.” (Monson’s Tracts - The
Northwest Passage, p.373)Finally, Prickett gives another clue when he
describes leaving the winter camp in June 1611. He states: “we wayed, and
stood out of our wintering place, and came to an Anchor without, in the
mouth of the Bay....” This would be consistent with sailing out of the small
wintering bay, into the mouth of another larger bay. He then continues the
sentence: “from whence we wayed and came to an anchor without in the Sea

There is one location which meets all of these criteria in the neighborhood of
52 degrees N latitude. This is the north side of Rupert Bay where it joins
James Bay and today is known as Pointe Goyeau. It is slightly south and
about thirty miles east of the location chosen by James for wintering on
Charlton Island.

Map 14 shows this area with contours at two meter intervals beginning at six
meters (the top of the shore line, given the six foot tide and assuming the
mean sea level is five meters above present level). Here is a bay with its head
to the north. There are three hills immediately adjacent to the entrance on
the north side. And there is a narrow gut between James Bay and the former
harbor separating the proposed camp location from the mainland, forming an
island. The island goes from approximately 51degrees, 43' to over 51 degrees,
47', so it is close to the 52 degrees mentioned by Monson.

It is also consistent with Prichett’s description as to how he proceeded to
locate a suitable place to haul the ship out for the winter. He states that he
went east to the bottom of the bay. While the bottom of the bay appears more
south than east when true north is at the top, in this area of the world the
difference between true and magnetic north can be quite extreme. In 1631,
Thomas James measured declination in Hudson Bay at 59 degrees 20
minutes North latitude as 17 degrees 40 minutes East. (Appendix to: James,
The Strange and Dangerous Voyage of Captaine Thomas James, 1633). This
means that when a compass shows north, it is actually pointing 17.40 degrees
east of true north. If we shift north 17 degrees to the right (east), the bottom
of the bay easily becomes east. Likewise, going south and southwest when
north is 17 degrees east would bring one to the bottom of the bay on the other
side. It was on this second trip to the south and southwest when Prickett
found a place to haul the ship. Map 14 also shows that the most gentle slope
(where the contour lines are the widest near the shore)(white mark) is the
area behind the hills at the north entrance.
Map 15 at the five meter line
shows that the basic outline of the six meter line for this area continues. This
represents the location of mean sea level at that time. The profile of the area
marked by a white line indicates a suitable slope for hauling in a ship as the
rise of the land is gradual.

Finally, we have the description of the exit in which the ship goes out of the
small wintering bay into the a larger bay - Rupert Bay. (“we wayed, and stood
out of our wintering place, and came to an Anchor without, in the mouth of
the Bay....”) This is likely because initially the ship would have been rigged
and loaded (particularly with ballast stones) in the smaller bay and once
ready, it could weigh anchor and sail to the larger bay, probably for final

Map 16 shows this area as it now looks from Google Earth. The area towards
the higher ground at lower left is the area estimated for Hudson’s winter
camp. The line in the middle running north to south is the water cut which
still exists between James Bay and Rupert Bay but which once entered the
small bay used by Hudson.
Map 17 shows a more detailed photo from the air
of this cut.

The data from James’ description strongly supports the conclusion that there
has been isostatic rebound of five meters over the last 400 years. The
description of Hudson’s campsite is also compatible with this analysis and
therefore supports it. Using the locations shown by these contour maps,
allows for the identification of the locations of the winter camps of Henry
Hudson and Thomas James.

1. Geomapapp has adjusted the radar data so that it is compatible with previously surveyed heights above sea level in the
same area. Contour lines can be set at whatever full meter interval is desired.

2. This assumes that five meters is the mean sea level in 1631, and given a tidal difference of two meters (six feet), the high
water mark would be six meters as the mean difference is one meter.

3. Map 11 is by Henry Hanwell. This map is from the Hudson’s Bay Company Archives, Archives of Manitoba, number HCBA
N5094. It is reproduced with its permission.

4. This photo was taken by the author from the plane of fellow Explorer Club member Jeff Clark.

5. Reprinted in Asher, p. 110.

6. Asher, p. 116.

Asher, G.M. “Henry Hudson The Navigator,” Bert Franklin, publisher 1860

Gough and Robinson, “Sea-Level Variation in Hudson Bay, Canada, from the Tide-Gauge Data,” Arctic, Antarctic and Alpine
Research, Vol. 32, No. 3 (Aug. 2000), pp. 331-335.

Kenyon, W.A., “The Strange and Dangerous Voyage of Captain Thomas James,”Toronto, The Royal Ontario Museum, 1975,
p. 8

Mitrovica, Forte and Simons “A reappraisal of post glacial decay times from Richmond Gulf and James Bay, Canada,”
Geophysical Journal International, (2000) 142, 783-800, at p. 789. Data from Fort George, and James Bay, Hardy, below 50

Rick, Vellanoweth, Erlandson, “Radiocarbon testing and the ‘old shell’ problem.” Journal of Archaeological Science, 32 2005
(1641-1648, at 1644).

Sella, Stein, Dixon, Craymer, James, Mazzotti and Dokka, “Observation of glacial isostatic adjustment in ‘stable’ North
America with GPS” Geophysical Research Letters, vol. 34, January 2007, at p. 3
Map 1: Lower James Bay
Map 2: Charlton Island
Map 3: Charlton Island
Map 4: Charlton Island
Map 5: Charlton Island
Map 6: Charlton Island
Map 7: Charlton Island with contour lines
Map 8: Charlton Island
Map 9: Charlton Island
Map 10: Charlton Island
Map 11: Charlton Island in 1804
Map 12: Inner Harbor
Map 13: Inner Harbor
Map 14: Hudson Camp Island with contour
Map 15
Map 16