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GEOLOGY OF THE FIRST DISTRICT. 
4. Sparry limestone,* highly crystalline in texture, and containing many fine fossils, 
5. Shale. 
6. Pentamerus limestone, capped by a thin siliceous stratum containing many fine fossils. 
7. Tentaculite limestone. 
8. Water limestones, 
9. Pyritous slates. 
There may be two or three subdivisions introduced with propriety, in consequence of 
marked changes in the organic contents, as well as in the mineralogical characters of masses 
lying between some of those above mentioned. The second Pentamerus limestone is between 
the Delthyris shale and the Scutella limestone. 
The Scutella limestone was so named by Professor Vanuxum in consequence of a fossil that 
abounds in it, and is characteristic of the rock, that has some resemblance in form to some of 
the scutellae. It was so called as a matter of convenience merely, to designate the rock. 
The fossil referred to is the pelvis, almost discoidal in form, of a species of encrinite. 
The limestone in which this fossil occurs is a grey, and in some places reddish, crystalline 
limestone, replete with encrinal and testaceous remains. The fossils are all crystalline car¬ 
bonate of lime ; and those that have been called scutellae, are white or red, and highly crystal¬ 
line, and from their size and prominent colors, attract the attention of observers when travel¬ 
ling along the road. These fossils are from one to two inches in diameter. 
The “ Delthyris shales” convey by their name an erroneous idea of their nature. They are 
slaty, compact, or finely granular grey and blue limestones, abounding in various testacea and 
coralline remains. 
Economical applications of the materials of this division. 
The materials in the Helderberg division that are applicable to useful purposes, are, 
1. Limestones, for building stone, 
2. “ “ marbles. 
3. “ “ common lime. 
4. Cement rock for hydraulic lime. 
5. Pyritiferous slate, for alum, copperas and sulphate of lime. 
Building stones and Marbles. 
The Pentamerus, Tentaculite and Water limestones, all afford fine building stones, which can 
be procured in blocks of large size, perfectly solid, and free from cracks or flaws, in many 
parts of the range of these rocks, which extends in a curved line one hundred and forty miles 
* This limestone, called by Mr. Gebhard Sparry limestone, is very diflferent in aspect and geological position from that called 
by this name by Prof. Eaton, and is the Scutella limestone, the upper member of the Delthyris shaly limestone. 
