TWEXHOFEL: expedition to the BALTIC PROVINCES. 307 



than corals. Brownish Kmestones with thin calcareous shale partings 

 succeed and at the top is a coral limestone, made up almost wholly of 

 these organisms. This coralline limestone, according to Schmidt 

 and Mickwitz, affords an excellent datum plane, which can readily 

 be followed throughout the entire district. Eastward it is said to 

 undergo dolomitization. About a mile west is a new quarry which 

 during the summer of 1914 was in operation, and where fossils are 

 more readily obtained. The lithology is about the same as the middle 

 portion of the Borkholm section and about six feet are exposed. 



Near Herkiill, northwest of the dwelling and on the east side of the 

 post road, is a small quarry in the Borkholm. Here the basal ex- 

 posures consist of a fossiliferous, crystalline gray limestone with 

 mammillary upper surface. Then follow fifteen inches of black shale, 

 containing fucoidal impressions, and above this three feet of crystal- 

 line, coralline, and crinoidal limestone with many poorly preserved 

 coral heads. The beds of this limestone are from two to ten inches 

 thick. 



The Herkiill locality made known by Schmidt lies southwest of the 

 dwelling, and the former exposures were made by a drainage ditch. 

 At the north end of this ditch Schmidt noted the occurrence of the 

 white Borkholm limestone in place. This is overlain by w^hat appear 

 to be thin-bedded limestones and shales which carry an abundance of 

 fossils. No rock is visible in place, but the debris from the ditch has 

 been stirred by plowing and the fossils are readily collected. Both 

 fauna and lithology are similar to that of the locality described in the 

 next paragraph. Schmidt further stated that the contact between 

 the Silurian (Jorden Schicht) and the Borkholm could be seen here, 

 the Jorden strata appearing at the top of the ditch near its midlength. 

 Nothing of this is now visible. 



The Nyby exposures, north of Hapsal, are the best that were seen 

 of the Borkliolm formation. The quarries are situated on a low 

 terrace north of the residence of the Nyby estate, and are readily 

 found by their nearness to an old stone windmill. 



The section exposed in these cj[uarries, given from the summit 

 downwards, is as follows: — 



1. Impure, dark gray, semicrystalline limestone in four to six inch 

 beds, separated by thin beds of gray shale. In places 50% of the 

 limestone consists of the stems of large crinoids. Four feet six inches. 



2. Impure, dark gray, poorly crystalline limestone (beds four to 

 six inches thick) and thinner beds of gray calcareous shale. Two feet. 



Fossils are extremely common throughout, particularly corals 



