141 

 HORTON BLUFFS SECTION. 



GENERAL DESCRIPTION. 



The Horton series, which here flanks the Southern 

 plateau, is exposed for nearly 3 miles (5 km.) along the 

 tidal estuary of Avon river in the section known as the 

 Horton Bluffs. 



Looking northwesterly from the Avondale shore, Cape 

 Blomidon, the westerly termination of the Triassic trap 

 ridge of North mountain, may be seen standing pro- 

 minently about 500 feet (152 m.) above the sea. The 

 contact of the trap with the underlying sandstone is there 

 about 200 feet (61 m.) above the valley floor. The low 

 country intervening between this picturesque ridge and 

 Avonport is a part of the Annapolis-Cornwallis Triassic 

 basin. The contact of the Triassic with the Horton 

 shales is concealed on the shore, but the low red bluff \ mile 

 (o-8 km.) to the north is made up of heavily cross-bedded, 

 wave-eaten, soft Triassic conglomerate of a dark grey 

 or chocolate colour, consisting of well worn pebbles up to 

 4 inches or more in diameter of sandstone, red shale, 

 quartzite and quartz, embedded in a matrix of subangular 

 quartz grains, and bound by a ferruginous calcareous 

 cement. The dips are gently northwestward. 



The underlying Horton beds rest in a flat syncline, of 

 which the northern limb is regular and moderately inclined, 

 while the southern limb, though at first but slightly dis- 

 turbed, becomes strongly folded and faulted against the 

 succeeding arkose series. At the beginning of the section 

 the black argillaceous or calcareous shales make up the low 

 banks and pave the tidal flat in an overlapping series of broad 

 plates. The average dip is here scarcely 7 . On numerous 

 bedding planes abundant flakes of mica are conspicuous. 

 Ripple marking is common; raindrop impressions may 

 frequently be observed; and sun cracking is not at all rare. 

 The most common fossils are the spore case of species of 

 Lepidodendra, which are extremely abundant is some of 

 the micaceous shales. Lepidodendron corrugatum Dn. 

 and Aneimites acadica, Dn. the two most characteristic 

 plants of the Horton, occur at various horizons, but they 

 are nowhere abundant. A species of Sphenopteris is rather 

 rare. In Dawson's collection occur in addition : Lepido- 

 dendron acideatum, L. sternbergi, L. dichotomum, L. elegans, 



