GEM DISTRICTS OF CEYLON AND BURMA—ADAMS 311 
again seen with an easterly dip of about 60°. This dip again de- 
creases to about 30° at Kathe and Mogok but in the lit-pas-lit gneiss 
in the valley of the Yaynee River, just south of Mogok, rises to 70°. 
In the section as shown in Figure 2 the dip is represented as gradually 
increasing from Kathe to the Yaynee. 
The strike of this limestone series on the road between Thabeikkyin 
and Mogok is not correctly shown by Barrington Brown,‘ but, as he 
states, before the construction of the road in question it was impos- 
sible to make accurate observations on the course of the limestone 
bands in this part of the area, owing to the very heavy fresh covering. 
A microscopic study of the rock specimens from Mogok, brought 
to England by Barrington Brown, was made by the late Prof. 
J. W. Judd. In their joint paper the whole tenor of Professor 
Judd’s description leads the reader to the conclusion that Judd 
believed that he had evidence from the microscopic studies of these 
rocks that the Archean limestones of Burma had originated from the 
alteration of certain pyroxene gneisses. Since the publication of this 
paper it has been repeatedly stated in print that this was the conclu- 
sion reached by Judd from his studies of the Mogok limestones. 
When preparing the present article the writer, in looking over 
some old papers, found a letter written to him by Professor Judd 
under date of November 4, 1896, evidently in reply to a communica- 
tion of his to Professor Judd, expressing surprise that he had 
reached such a conclusion. In this letter Professor Judd writes: 
“T must disabuse your mind of the idea that I want to put forward 
a theory to cover all the metamorphic limestones of Archean age. 
I do not think such a chemical theory as I have suggested at all 
likely to meet the case of the enormous mass of limestone regularly 
bedded over vast areas like those mentioned by Barrington Brown 
in Burma, or referred to by you in Canada. It is the special thin 
bands that contain rubies, spinels, and other marketable minerals 
that I am referring to.” This letter is perhaps worthy of mention as 
no one would discover from a perusal of Professor Judd’s paper that 
he intended by his theory to account merely for certain small streaks 
of limestone in the Mogok series and not for the whole succession 
of bedded limestones which are so strikingly displayed in this 
region. 
That enormous developments of bedded limestones, such as those 
found in the great series under discussion, really represent highly 
altered and very ancient sediments is borne out in all respects by a 
study of their field relations, a conclusion which is also reached by 
LaTouche® in his study of the geology of the northern Shan States. 
‘Barrington Brown and Prof. John W. Judd: ‘‘ The rubies of Burma and associated 
minerals.” Phil. Trans., Royal Society, vol. 187, 1896. 
® Records of the Geological Survey of India, Vol. XXXVI, pt. 3. 
