Geology Reference
In-Depth Information
personal boy also have bedding and that goes with one of the
lighter boxes. Sixty pounds each is the most that a native will
carry.
I have a jolly little personal boy just now. My others hav-
ing been rotten, I sacked them. This one is called Morweha
which means 'Bring it here'! I am greatly looking forward to
making this little trip on my own. I am only going about
30 miles from here and shall work in the district for a week
and then move south until Mr. Barton lets me know further
plans. I shall be too busy to be lonely, and any how I have
a boy Ali who speaks very good English. I can also speak
Makua fairly readily now - tho' I find it difficult to understand,
they talk at such a prodigious pace.
Holmes greatly enjoyed this first opportunity to work on his
own. The district contained ancient Precambrian rocks that had
never previously been examined, and his work went a long way
towards determining the secrets of the geology of this extra-
ordinary country. He collected samples of the di¬erent rock
types, some of which the natives crushed in a large iron mor-
tar. He then panned the crushed material in the hope of finding
minerals of economic worth, particularly radioactive ones. But
the search for radium and thorium proved as elusive as the
search for any other minerals of economic importance, and hav-
ing explored the river where Starey had found the original sam-
ple Holmes discovered
'to my disappointment that my thorite
is a mixture of hypersthene and tourmaline',
two common min-
erals of no economic value. Alas, he was not going to save
Memba Minerals after all. He does not record, however, how
this news was received back at the base camp!
Although unsuccessful in finding radium, the heavy residue
left in the panning bowl often contained zircons, a mineral ideal
for age determinations. These were sent back to the lab and later
analysed by Holmes, allowing him to understand the age rela-
tionships of these ancient rocks not only to each other, but to
Precambrian rocks around the world. The six months of geolo-
