HILL: GEOLOGY OF JAMAICA. 61 



Mollusca are most abundant in the " Bruggadoo, " as the black clays 

 at the railway cut where so much slipping has occurred are called. 



Chapelton Beds. 



In Clarendon Parish, at Chapelton, and in the slopes of the Minho 

 River east of that town, beds allied to the Cambridge formation are 

 exposed. These present two subdivisions, the upper of wliich consists 

 of more or less massive beds of yellow foraminiferal (Orbitoidal) marl 

 alternating with bedded yellow limestones and gi-ading up into the 

 white Montpelier limestones ; the other is mostly composed of creeping 

 blue, black, and red clays known in Jamaica as " Bruggadoo," resem- 

 bling similar material of the Catadupa section, and in which occasional 

 fossiliferous calcareous layers only an inch in thickness and a few yards 

 in length are exposed. 



The higher subdivision has its typical occurrence along the main 

 street of the village of Chapelton, between Chapelton Hill and the Eiver 

 St. Thomas. The second is exposed along the "lower" road which 

 parallels the foregoing street but follows a lower contour in the valley 

 of the Minho. The following local section of this subdivision was ob- 

 served at Chapelton, between the hill in Chapelton upon which the 

 residence of the Inspector of Constabulary is situated, and the bed of 

 St. Thomas River two miles north. This section is the upward con- 

 tinuation of the general Clarendon section given on page 46. The 

 thicknesses given are approximated : — 



3. Bed of yellow marl and thin limestone alternating, containing Feet. 



Orbitoides and small Ostrea, estimated thickness .... 185 



2. Blue and purple clay 115 



1. Yellow marl, clay, and limestone 75 



At Mr. Craig's estate in the river valley a considerable mass of yellow 

 limestone (No. 1) is exposed, but it was impossible to find determinable 

 fossils therein, or to decide the exact position of this mass relative to the 

 clays. It was our impression that it occurred about midway in the 

 general section. Down the valley slope, on the so called lower Chapelton 

 road, which follows the river and cuts into beds lower than those of the 

 above section, many isolated cuts are exposed, composed entirely of the 

 blue and purple clays, with an occasional thin local layer of yellow clay 

 containing cruml)ling fossil oysters, Carolia, and Foraminifera. From 

 reasons given in the paleontologic discussion, these lower beds are sup- 

 posed to be equivalent to those of the Catadupa section, and the upper 

 are a hie:her extension of the same. 



