THE AGATE BAY BEDS. 289 
IB. Stratiform laumontitic amygdaloid, the irregular and non-continuous 
layers less than six inches in thickness. Matrix much as in fore- 
going; finer grained. Amygdules small, not exceeding } inch, 
thickly crowded, of laumontite, calcite, saponite. Thickness... -- 10 
IIA. Massive, vertically columnar layer, of a rock similar to that of 1A., but 
finer grained. In places laumontite amygdules or pseud-amyg- 
dules run through the whole thickness. Subordinately stratiform 
when weathered. Thickness.................. See heir sie es 3 
IIB. Stratiform amygdaloid like 1m. Thickness ........... x SEE ate 6 
— 9 
IIIA. Massive, vertically columnar layer of a rock closely resembling that of 
IA., but showing under the microscope larger olivines and more 
pseud-amygdaloidal chlorite. Exceedingly irregular in thickness, 
expanding and contracting suddenly from a few inches to several 
feet, and vice versa. Thickness from 4 inches to..-...--.--.--- eas 
ITB. Stratiform laumontitic and calcitic amygdaloid; subordinate layers a 
TEWeINGHessuhiGk. ME NICKNESS tere [acy ete Sere eater aera ial init 6 a 
IVA. Massive, vertically columnar layer like IA., ILA., IllA.; exceedingly ; 
irregular in thickness, running from nothing to.......---..-.--- 2 
IVB. Stratiform laumontitic amygdaloid, the amygdules larger than usual, 
reaching 4 inch, and evenl inch. Thickness..... .............20 = 
VA. Massive, vertically columnar layer; rock like that of I4.; very irreg- 
Wibie, WUNRIESS, WOW NINE? iO) sond0s boocobee ceoo {See oL coe ecce 2 
VB. Stratiform laumontitie and calcite amygdaloid; layers so thin as to 
near sielhe “WNC 6S isscbéeadeccoo cbcnoe deaaeo cdaseones Bibs 
5 
VI. Massive, vertically columnar layer, somewhat amygdaloidal towards 
EOP ROC Ka lc UACm een NTC IMESS ie ere asjois siaistelctetolelaini= Seoteey nsayeten ay eis 15 
VII. Red shaly sandstone; very irregular in thickness; running away down 
into crevices in the underlying massive rock, and in places curi- 
ously intermingled with the overlying amygdaloid. Thickness ... 2 to3 
VIII. Stratiform laumontitic amygdaloid, layers at times very thin. Thick- 
MGSS mises a efetas sre Bos Bete SSIS BR Ee Aa IO GODS Ae aoorE Shee sta e 10 
IXA. Massive layer, with the vertically columnar structure strongly marked, 
of a fine-grained dark-gray to nearly black rock, which under the 
microscope is seen to be one of the usual olivine-bearing mela- 
phyrs, peculiar only in unusual fineness of grain. This layer forms 
the greater part of the face of the west point of Agate Bay. It is 
exposed in an immense surface, sloping towards the lake, as much 
as a quarter of a mile in length, and at times several hundred feet 
wide. As one walks over this great surface the ends of the col- 
umns, which show in cross-section, are finely displayed, and are seen 
to lack, as usual, the regularity of the basaltie columns of some 
regions. They are made by the intersections of several systems 
of joints, here quite close, and have varying numbers of sides 
19LS 
