?5 
S'Sli. There are also sheets of an iutrusiYe ‘ greenstone,’ which has undergone great 
^ teration. Most of the sedimentary rocks arc more or less pyritous, some of the shales 
^^pecially being full of small cubical crystals of iron pyrites, and most of them, too, 
calcareous. This is especially the case with the sandstones, greywackes, and con- 
Srnmerates, and with some of the shales. The faces of the ‘ joints ’ or cracks in the 
^ocks are almost invariably coated with carbonate of lime in the form of calcite. 
_ “ The strata dip with great regularity at an average angle of from 20° to 22°. 
c the northern portion of the field the direction of dip is, as a rule, a little to the 
^°^th of east ; on the southern portion it is to the E.S.E. 
“ While many of the rocks have undergone but little alteration, others have been 
Sieatly altered, almost to the obliteration of their original character. These rocks have 
ccome indurated and in some cases semi-crystalline, and it is only with difliculty that 
’c latter can bo distinguished from the true igneous rocks. Speaking generally the 
ocks which occupy the lowest position in the series, and whose outcrops occur, there- 
the western portion of the field, have undergone the greatest alteration ; 
lough in the uj)per part of the series rocks which have been considerably altered 
^wrate with those which have undergone but slight alteration. 
Perhaps the most typical section of the G-ympie rocks is that which is taken 
^ a line (A-B) across the field from near the Railway Station to near Chanuon-street 
ndge (pi_ 5^,^ following list of rocks in the section the thicknesses 
^ ave been calculated from the outcrop of the strata at the surface, as very little mining 
rj on now in this part of the field, and the old workings are generally inaccessible. 
. ® Hguros are therefore only approximate, and the thicknesses vary greatly on either 
tie line of .eetion,- 
'Phoenix Slates 
' (202 ft. 4 in. thick) ' 
Pine impure limestone (fossiliforous)... 
Coarse pebbly conglomerate with sandstone (very thick at station) 
Laminated sandstone 
Shales (fossiliferous) 
Coarse altered conglomerate ... 
Shales with beds of thin-bedded sandstone 
Hard grey groywacke 
Shales (fossiliferous) 
Coarse pebbly conglomerate 
Laminated fine-grained sandstone 
^ngular grit (probably a volcanic agglomerate) 
Greenish and higlily fossiliferous sandstone 
Greenish semr-crystallino grey wacko... 
Shales, so-callcd ‘ First Bed of Slate ’ 
Hard grey groywacke 
oarso altered conglomerate ... 
rcenisb semi-crystalline groywacke ... 
andstone and coarse altered conglomerate 
^ales, so-called ‘ Second Bed of Slate ’ 
arcl altered crystalline greenstone — ‘ Gympie greenstone 
•■ecn and purple altered chloritic rock; partly amygdaloidal volcanic 
rocks, partly volcanic ash, and partly stratified 
“•Called ‘ Third Bed of Slate ' with a thickness of grey-green, finC' 
grained groywacke, and underneath altered chloritic rocks like those 
above 
Limestone.. 
138 
3G0 
55 
56 
10 
50 
20 
- GO 
26 
20 
26 
33 
25 
15 
19 
20 
16 
20 
13 
297 
315 
286 
20 
6 
0 
0 
4 
0 
0 
0 
0 
3 
0 
4 
0 
0 
2 
8 
0 
6 
3 
0 
0 
0 
0 
0 
1,909 0” 
