Clais Mhadaidh is one of the many 'dry gullies' of the Cairngorms formed by glacial-meltwater during the deglaciation period. Clais Mhadaidh is a typical 'dry gully' of the Cairngorms - steep sided, and well able to conceal a terrace of two-story buildings at its deepest, and widest point.
Clais Mhadaidh runs from the south-western flank of Carn a' Mhaim almost due south towards the Dé. The upper-reaches of the hollow cuts off, and captures the westbound burn issuing from Lochan Féith nan Sgòr, making this lochan the source of Allt Clais Mhadaidh.
The Gaelic word Mhadaidh - means wild dog, but in the context of this place name Clais Mhadaidh - means hollow of the wolf. In Gordon (1925) the author refers to the hollow while describing his route between Glean Laoigh Beag, and Gleann Giubhasachain - writing :
... to Glen Giusachan the way was across heather and rough stones. One descended several hundred feet to Glen Dee, crossing on the way the curious and far-stretching hollow known as Clais a' Mhadaidh, or the Wolf's Hollow
- Gordon (1925) (p124-p125)
The deepness of Clais Mhadaidh was taken advantage of during the Gleann Giubhasachain deer drive, when deer were driven down the glen towards the mouth, and men with rifles positioned along the edge of the hollow (Gordon (1925), p208).
Interestingly - the other hollow in Mar Forest named Clais Mhadaidh is in Gleann Laoigh - where, apparently the use of Mhadaidh commemorates the killing of the last native wolf in Mar Forest.