Geographic positioning
The source of the following topographic information
is the 1:250,000-scale
Provisional Geological Map of the Tucker Glacier
Pearl Harbour Region,
dated June 7, 1963,
drawn by Gerald Holdsworth
for the NZ Department of Lands and Survey.
Gerald prepared this map after returning from Antarctica,
based on the topographic survey and geological information
collected from the exploration area.
The map covers some 3000 square miles (7800 sq km)
of terrain in Northern Victoria Land.
Listed below are geographic positions
of various features in the exploration area.
The author scaled listed latitudes and longitudes from Gerald's map.
These positions have no official status.
Campsite positions for Holdsworth's team,
and intervening straight-line distances and bearings.
Example 1: The Depτt lies at latitude 72°16'35S, longitude 165°43'20E.
Example 2: Camp I lies 5 km from the Depτt at a bearing of 308°.
Location ..... Dist Bg. Latitude,S Longitude,E
Depτt .................. 72°16'35 165°43'20
Camp I ....... 5 km 308° 72°14'55 165°36'40
Camp II ...... 8 km 347° 72°10'35 165°33'30
Camp III .... 12 km 318° 72°05'50 165°20'00
Camp IV ..... 15 km 321° 71°59'35 165°04'10
Camp V ...... 20 km 293° 71°55'15 164°32'10
Camp VI ...... 9 km 192° 72°00'00 164°28'40
Camp VII .... 11 km 134° 72°04'00 164°42'00
Camp VIII .... 7 km 134° 72°06'45 164°51'00
Camp IX ..... 18 km 127° 72°12'45 165°16'50
Depτt ....... 16 km 115° 72°16'35 165°43'20
Camp X ...... 16 km 45° 72°10'25 166°03'20
Camp XI ..... 21 km 83° 72°09'10 166°40'10
Camp XII .... 11 km 118° 72°12'05 166°57'40
Camp XIII ... 10 km 113° 72°14'15 167°14'40
Camp XIV ..... 6 km 99° 72°14'45 167°24'30
Airlift point 28 km 84° 72°13'15 168°14'10
Distances shown are straight line distances between campsites, totaling 213 km.
Actual sledging distances are slightly greater due to the curved paths.
Distances walked or skied from campsites to survey stations, etc., are additional.
See below for discussion of the estimated accuracy of geographic locations.
Features named after expedition members and supporters
Location ................. Latitude,S Longitude,E
SE end of Millen Range .... 72°29'35 166°35'20
Peak on Millen Range ..... 72°17'35 166°07'10
NW end of Millen Range(H2) 72°04'35 165°20'00
Mt. Holdsworth 2370 m (AC). 72°06'25 165°40'30
Mt. Pearson 2450 m (AG) ... 72°14'55 166°45'30
LeCouteur Peak ............ 72°06'40 165°49'40
Leitch Massif 2180 m (RR2). 71°54'35 164°27'00
Mt. Hayton 2260 m (FF2) ... 72°00'15 165°00'00
Mt. Brenda Watt secretary 72°25'55 165°51'50
Mt. Tararua 2548 m ........ 72°04'20 166°03'50
Mt. Aorangi 3131 m ........ 72°22'55 166°17'30
JATO Nunatak (F2A)US Navy 72°19'20 165°31'20
Peak overlooks Joice Icefall
Peak overlooks Lloyd Icefall
Survey station designations are parenthesized., e.g., (Q2A) denotes survey station Q2A.
Other named features and triangulation stations
Location ................. Latitude,S Longitude,E
Cirque Peak (I2) .......... 72°07'45 165°43'00
Crosscut 2970 m (O2) ...... 72°19'50 166°12'10
Gothic Peak (QQ2).......... 71°59'30 164°33'00
Homerun Bluff.............. 71°48'15 166°37'40
Pyramid Peak (G2).......... 72°14'05 165°19'30
Sphinx Peak (X2)........... 72°15'15 165°23'10
Turret Peak (N2)........... 72°14'40 165°49'40
E2 (landmark).............. 72°12'00 165°40'20
AD (landmark).............. 72°09'15 167°01'30
EE2 (nunatak).............. 72°05'55 164°56'10
LL2 (nunatak).............. 72°01'45 164°42'40
Q2A 2900 m (nunatak)....... 72°09'45 165°38'20
VV2 (nunatak).............. 72°12'45 165°13'20
YY2 (landmark)............. 72°13'35 165°07'00
Other locations for comparison
Location ................. Latitude Longitude
South Geographic Pole ..... 90°00'S Indeterminate
North Geographic Pole ..... 90°00'N Indeterminate
South Magnetic Pole (1962). 66°57'S 142°35'E
Scott Base ................ 77°50'S 166°50'E
Christchurch airport ...... 43°29'S 172°31'E
Singapore airport .......... 1°21'N 103°59'E
Mapping and surveying principles
The following discussion attempts to address
the surveying and mapmaking process,
which was used to produce the above-described map.
Although the map shows geologic features,
geologic mapping is not discussed here.
For simplicity, consider the map as a bird's-eye-view,
as if the Earth were flat.
To help explain the surveying and mapmaking process,
let us follow the process in reverse order,
starting from mapmaking,
and working back to the collection of survey observations.
Imagine a vertical aerial photograph of the terrain to be mapped.
The imaginary photo is taken from a great distance,
so as to be free from distortion present in actual aerial photos.
For example, in actual aerial photos,
highlands are closer to the camera than lowlands,
so highlands appear larger,
i.e., the photo shows highlands at a larger scale than lowlands.
Scale variation in aerial photographs is an example of distortion.
Instead, assume that our imaginary photo
shows to a consistent scale all features of the landscape
that the finished map is to show,
like glaciers and mountains.
If the photo is covered with tracing paper,
landscape features can be traced from the photo.
Further, if the distance between any two points on the photo is known,
a distance scale can be constructed for the aerial photograph,
and also for a map that is traced from the photo.
Now, take a conceptual step backwards
from mapmaking towards surveying.
For that purpose, select prominent landmarks on the photo,
often mountain peaks
such that every point on the terrain
is visible from at least two landmarks.
On the tracing paper placed over the photo,
draw a dot at each selected landmark.
Then, draw a line from every landmark dot
to every other landmark dot,
so as to construct a network of lines.
Lines drawn on the tracing
represent the lines of sight between the landmarks.
Each landmark has lines spreading outwards
to the other landmarks,
like rays from a sunburst.
Triangulation
A network of lines interconnecting landmarks forms a maze of triangles.
On a photo, a protractor can measure the angles of each triangle.
For surveying in the field,
the theodolite measures angles from each landmark
between lines of sight to the other landmarks.
In the field, at each survey station,
the theodolite is sighted to every other visible landmark,
to measure the angle between every pair of visible landmarks.
Each pair of visible landmarks
together with the survey station occupied
form a triangle over the terrain.
The theodolite has measured one angle of that triangle .
Eventually, the theodolite will have occupied
every accessible landmark,
and measured the angles to the other visible landmarks.
Now, the angles of all the triangles in the network are known.
This process is called triangulation.
A triangle is a rigid shape.
So fixing the angles fixes the shape,
and the lengths of the sides are in fixed proportion.
Thus, a network of triangles interconnecting landmarks
constructs a rigid framework over the terrain that it covers.
In a similar sense, a distortion-free aerial photograph
is a rigid image of the terrain that it covers.
However, such a framework does not, by itself,
convey the scale of the terrain.
To get the scale of the framework,
recall that for a distortion-free aerial photo
a single known distance between any two points
enables a distance scale to be constructed for the entire photo.
Similarly, a single known distance
between any two landmarks in a network
fixes all distances between landmarks in the network.
These distances are computed by trigonometry,
a branch of mathematics.
Direct measurement between landmarks on widely-spaced peaks
is impractical with the available surveying equipment.
But if we measure the distance between two closely-spaced landmarks
that distance can be extended throughout the entire network.
Baseline
Two of the landmarks are deliberately placed close together
such that direct measurement of their spacing is practicable.
Such measurement is called chaining the baseline,
because a calibrated steel tape called a chain is used to measure the distance,
and the interval between the landmarks is called the baseline.
Baseline landmarks are usually a mile or two apart
on a smooth, level snow surface
on the polar plateau, or on a glacier.
Gerald's team chained three baselines as a check on accuracy,
but this discussion considers only one baseline.
Theodolite readings from each end of the baseline
to the opposite end of the baseline
and to surrounding survey landmarks,
such as mountain peaks,
enable the ends of the baseline
to be included in the network.
A snow cairn is constructed at each end of the baseline.
Topographic detail
A map that shows only landmarks
is hardly suitable for general use,
but it serves as a skeleton
for filling in intervening topographic detail,
such as mountains and glaciers.
The detail comes from:
aerial photos (by aerial photogrammetry),
photo panoramas from landmarks (by terrestrial photogrammetry), and
sketches that Gerald prepared at each survey station.
Aerial and terrestrial photographs
help fill in intervening detail between the landmarks,
using the techniques of photogrammetry.
Gerald's patient hours with binoculars preparing sketches,
identify the landmarks and describe the intervening terrain
even more perceptively than the photographs.
Geodesy
Brief mention is made of geodesy,
which concerns the issue
of mapping the curved Earth's surface
on a flat sheet of paper.
Gerald drew his map of the exploration
area on a sheet
as if the sheet had been wrapped around part of the Earth,
in contact with the Earth along a parallel of constant latitude
such that the sheet formed part of the surface of a cone.
The conical projection that Gerald used
causes some effects visible in the map:
north-south meridians converge from top to bottom, and
east-west parallels to arch (in the southern hemisphere).
Such behavior of the meridians and parallels
provides visual evidence of the curvature of the earth.
Polar surveying techniques
Notes on this topic were eliminated, because:
Surveying methods used are now out-of-date; and
Ground control for polar mapping is now complete.
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