Question: What sort of geological formation housed a clan that was responsible for the murder of over 1000 people in Scotland between the 13th and 16th centuries?

Context paragraphs:
Kačić noble family: The Kačić family (Croatian: "Kačići" , Hungarian: "Kacsics" , Latin: "Cacich" ) was one of the most influential Croatian noble families, and was one of the Croatian "twelve noble tribes" described in the Pacta conventa and Supetar Cartulary.  The historical sources refer to members of this family as nobles in the area of the Luka županija in the Zadar-Biograd hinterland (12th–16th centuries), as the lords (knezes) of Omiš (12th and 13th centuries), and as the lords of the Makarska Riviera (15th and 16th centuries).  Another prominent branch of the family was part of the Hungarian nobility.

MacDonnell of Antrim: The MacDonnells of Antrim (Gaelic: "Mac Domhnaill"), also known as the MacDonnells of the Glens, are a branch of the primarily Scottish-based Clan Donald in Ireland.  Initially part of Clan MacDonald of Dunnyveg (Clan Donald South), the MacDonnells of Antrim became their own branch in 1558 when Somhairle Buidhe MacDonnell obtained the lordship of the territory in Ireland from James MacDonald, 6th chief of the Clan MacDonald of Dunnyveg.  The MacDonnells of Antrim were a sept of the powerful Clan Donald of the royal Clann Somhairle, (see Lords of the Isles), that the English crown had attempted to cultivate since the early 14th century in its efforts to influence the course of politics in Scotland.  The MacDonnells established a growing presence in Ireland throughout the 15th and 16th centuries, and played a crucial role in the politics of 17th century Ireland.  Today the surname is predominantly spelled McDonnell in Ireland and abroad.  Many of the present day McDonnells have a common descent from Sorley Boy MacDonnell.

Huajiying Formation: The Huajiying Formation is a geological formation in Hebei, People's Republic of China.  Known for its fossils including primitive birds, the age of the formation is uncertain.  It may represent an early portion of the Jehol Biota, dating to somewhere in the early Cretaceous or late Jurassic periods.  It may correlate with the early Cretaceous Dadianzi Formation and parts of the Yixian Formation, with an age range between 140 and 122 Ma ago.  It contains the Qiaotou Member, sometimes treated as a distinct formation.

Tiaojishan Formation: The Tiaojishan Formation is a geological formation in Hebei and Liaoning, People's Republic of China, dating to the middle-late Jurassic period (Bathonian-Oxfordian stages).  It is known for its fossil plants, and is made up mainly of pyroclastic rock interspersed with basic volcanic and sedimentary rocks. Previously, the Tiaojishan Formation was grouped together with the underlying Haifanggou Formation (also known as the Jiulongshan Formation) as a single "Lanqui Formation."

Ledford, Illinois: Ledford is an unincorporated community in the Harrisburg Township, Saline County, Illinois, United States situated between Carrier Mills and Harrisburg, Illinois.  It was named after a well known Ledford family in the area.  In the late 19th and early 20th centuries, the peak of the coal boom in Saline County, it was a thriving mining center home to more than 1000 people.

History of Transylvania: Transylvania is a historical region in central and northwestern Romania.  It was part of the Dacian Kingdom (1st–2nd centuries CE), Roman Dacia (2nd–3rd centuries), the Hunnic Empire (4th–5th centuries), the Kingdom of the Gepids (5th–6th centuries), the Avar Khaganate (6th–9th centuries) and the 9th century First Bulgarian Empire.  During the late 9th century, western Transylvania was reached by the Hungarian conquerors and later it became part of the Kingdom of Hungary, formed in 1000.  After the Battle of Mohács in 1526 it belonged to the Eastern Hungarian Kingdom, from which the Principality of Transylvania emerged.  During most of the 16th and 17th centuries, the principality was a vassal state of the Ottoman Empire; however, the principality had dual suzerainty (Ottoman and Habsburg).  In 1690, the Habsburgs gained possession of Transylvania through the Hungarian crown.  After 1711 Habsburg control of Transylvania was consolidated, and Transylvanian princes were replaced with Habsburg imperial governors.  After the Austro-Hungarian Compromise of 1867, the separate status of Transylvania ceased; it was incorporated into the Kingdom of Hungary (Transleithania) as part of the Austrian-Hungarian Empire.  After World War I, Transylvania became part of Romania.  In 1940 Northern Transylvania reverted to Hungary as a result of the Second Vienna Award, but it was reclaimed by Romania after the end of World War II.

Little Wymondley: Little Wymondley is a village situated between Hitchin and Stevenage in Hertfordshire, England.  Paradoxically, it is larger than its near neighbour Great Wymondley.  It has several interesting houses, including the moated Bury of the 16th and 17th centuries, the fine 17th century Hall, the late Georgian Wymondley House, and Wymondley Priory, an early 13th century foundation turned into a house in the 16th and 17th centuries.  At the 2011 Census the population of the village eas included in the civil parish of Wymondley.

Falnama: Falnama is a book of omens used by fortune tellers in Iran and Turkey during the 16th and 17th centuries.  Individuals seeking insight into the future would engage in a series of purification rituals, turn to a random page in the Falnama, and interpret the text and drawings thereon for good or ill.  Falnama manuscripts were primarily created during the 16th and 17th centuries as the Islamic calendar was approaching the year 1000.

Sawney Bean: Alexander "Sawney" Bean was said to be the head of a 48-member clan in Scotland anywhere between the 13th and 16th centuries, reportedly executed for the mass murder and cannibalisation of over 1,000 people.

Bennane Head: Bennane Head is a tapering piece of land projecting into the Firth of Clyde, Scotland.  Its headland extends into the Firth of Clyde at the northern end of Ballantrae Bay, 17 km southwest of Girvan.  A 200 m cave near Bennane Head is said to be the place, where the cannibal Sawney Bean and his family lived in the 15th century.

Supporting paragraphs: Bennane Head Sawney Bean
Answer: cave