A, R. Andrew—The Dolgelley Gold-belt. 167. 
Llanelltyd westwards to Barmouth the general strike is in the main 
more north-easterly (45° or 50° east of north). This general flanking 
structure is much complicated by the minor folding to which the 
strata have been subjected. This folding has given rise to minor 
anticlines and synclines, often broken by small faults, especially along 
their axes, where, instead of gieldns to the pressure by bending, the 
strata have snapped. 
~The faults found in this district may be divided for convenience 
into two classes— 
(a) Minor faults or fractures. 
(b) Major faults or throw faults. 
The minor faults have probably been formed during the upheaval 
of the dome. They occur along those lines where the beds have 
been fractured, but where the pressure to which they have been 
subjected has not been sufficient to produce a relative displacement 
of the beds on the two sides of the fault. Among the harder beds 
of the Lower Cambrian they are especially numerous, crossing one 
another at all angles. In the beds of the Middle and Upper Cambrian 
they are not so frequent, as the strata there are not so massive, 
and have been more readily thrown into folds. ach of these fractures 
forms a noticeable groove along its outcrop. 
Of the major faults or dislocations there are two main sets, with 
a third less important set— 
1. East and west faults (practically 70° E. of N.). 
2. North-east and south-west faults (30° E. of N.). 
3. North and south faults. 
1. Hast and West Faults.—These are almost certainly older than the 
others, for they are sometimes cut and dislocated by them. The most 
conspicuous one of this east and west set is the Cwm Mynach fault, 
which cuts out a great amount of the Lower Cambrian rocks. At its 
western end it is seen in the Maentwrog Beds; going eastwards it 
increases in throw, and on the Clogau Hill it cuts out fully one-half 
of the Gamlan Beds. As the fault is traced eastwards, it decreases in 
amount, and then disappears; it cannot be seen more than 5 miles 
away from its westerly extremity. 
2. North-east and South-west Faults.—Instances of this set of faults 
are seen in the country behind Bontddu, but the displacement they 
cause is by no means large. They are probably contemporaneous with 
the north-east and south-west gold-lodes, for at Bwlchcochuchaf 
and Hafoduchaf there is a close relationship between one of these 
faults and the lodes which I describe later under these names. The 
north-east and south-west faults were formed after the east and west 
ones, as is seen in the country behind Bontddu. 
3. Worth and South Faults —These are the most recent and con- 
spicuous of the faults of the Dolgelley Gold-belt. They are found 
throughout the district, but are of greatest importance towards the 
north-east. The chief faults of this set are the following :— 
- (a) The Llynbodlyn fault of Lapworth and Wilson extends from the 
estuary at Caerdeon to Llynbodlyn on the west of Diphwys, a distance 
of about 4 miles. It cuts several lodes and causes a considerable dis- 
placement of the sedimentary beds. 
