Abstract:
An erosion control block having male tab members and female socket members providing an interlocking relationship with neighbor blocks so that lateral removal therebetween is prevented. The erosion control block includes cable channels formed therein from respective opposite corners of the block so that an axis of the cable channels forms an “X” in said block.

Description:
RELATED APPLICATION 
   This patent application is a divisional of patent application entitled “Method of Forming A Mat of Erosion Control Blocks.” filed Feb. 17, 2004, and accorded Ser. No. 10/780,433, now U.S. Pat. No. 6,955,500. The subject matter of the pending application is incorporated herein be reference. 

   TECHNICAL FIELD OF THE INVENTION 
   The present invention relates in general to erosion control blocks, and more particularly to an interlocking erosion control block with cable channels formed therein. 
   BACKGROUND OF THE INVENTION 
   The erosion of soil, sand and other earth material has been controlled for many years by the use of erosion control blocks. The prior art is replete with erosion control blocks of all types, shapes and sizes. The primary function of erosion control blocks is to partially cover the ground to be protected and slow the flow of water thereover. A porous geotextile fabric is first laid on the ground. Depending on the area of the ground to be protected, the erosion control blocks can simply be hand laid on the fabric close together so that the weight of the blocks prevents shifting thereof under heavy water flow conditions. If the erosion control blocks have openings formed from the top to the bottom thereof, then eventually vegetation can grow through the openings and further anchor the blocks to the ground. 
   In other applications, the erosion control blocks are used in water channels or watershed areas that carry water on a normal basis. In this instance the blocks cannot be hand laid, except with the use of divers. More generally, erosion control blocks are cabled together into mats at the site and then lifted by a crane and lowered into the underwater location. In this case, divers may have to secure the edges of the adjacent mats together to form a single wide area mat. Mats of erosion control blocks can also be cabled together at a plant and transported to the site where a crane lifts the mats from a truck and lowers them into the area to be protected. Because the blocks are cabled together, a large volume of fast moving water can be accommodated without erosion of the underlying soil. 
   When a mat of erosion control blocks are cabled together and lifted by a crane, or the like, the mat bows downwardly in the middle. As can be appreciated, the cabled blocks tend to migrate downwardly to the middle of the mat due to the weight of the individual blocks. It is crucial that the blocks of the mat do not engage each other in such a manner that they become cracked, chipped or broken. This is especially important with blocks that otherwise interlock with each other, such as the type disclosed in U.S. Pat. No. 5,556,228 by Smith. It is important that a mat of such type of interlocking erosion control blocks be cabled and lifted without undue twisting or turning of the blocks on the supporting cables. If the blocks are subjected to torsional forces while being interlocked, such as when lifted in a mat, then the arms and/or sockets of the individual blocks can be damaged or broken. Damaged or broken blocks of a mat compromise the structural integrity of the mat. Moreover, it is time consuming and expensive to uncable a mat and replace or repair damaged blocks. 
   It has been an established practice to form the erosion control blocks with two or four cable channels therethrough. When two cable channels are formed in the blocks, then they are generally formed orthogonal to each other (North-South and East-West) so that the cables can be strung through a number of blocks in an array, or mat, parallel to the sides of the mat. This represents a rather unstable situation for the blocks, as they tend to rotate a small amount about the cables. This instability is alleviated by forming blocks with two parallel cable channels running East and West, and two other parallel cable channels running North and South. This reduces the instability of the blocks, and is suitable for blocks that are not of the interlocking type, such as disclosed in the patent identified above. Even with two parallel cables extending through each block in a N-S/E-W direction, the cables themselves tend to move with respect to each other in a torsional manner, thereby allowing the blocks to rotate a small amount. The rotation of interlocking blocks is undesirable, and should be avoided. 
   From the foregoing, it can be seen that a need exists for a method of cabling a plurality of erosion control blocks together to minimize rotation thereof. Another need exists for a method of cabling interlocking blocks together in a mat to minimize rotation of the individual blocks. Yet another need exists for a method of forming erosion control blocks with cable channels to accommodate the cabling methods disclosed herein. 
   SUMMARY OF THE INVENTION 
   In accordance with the principles and concepts of the invention, there is disclosed an erosion control block constructed for cabling a number of such blocks together in a matrix or mat. 
   In accordance with one embodiment of the invention, disclosed is a generally rectangular-shaped erosion control block adapted for cabling to other similar blocks, where the blocks have diagonal cable channels formed therethrough. With this arrangement of cable channels, the cables threaded through the cable channels exit the blocks at the respective corners thereof. The blocks of the mat are thus individually more stable and resistant to torsional movement. 
   In accordance with another feature of the invention, the erosion control blocks are of the interlocking type having male tabs that interlock with female sockets. The blocks each have a central opening through which the cables extend. The openings, especially at the side and edge blocks of the mat, facilitate attachment of the various cable ends to other cables of the mat. 
   In accordance with another aspect of the invention, disclosed is an erosion control block formed of a heavy material, and having at least four sides, and a top surface and a bottom surface. The block has formed on at least one side of two sides a respective male tab member extending therefrom. The male tab member includes a neck portion and an enlarged end. Two other sides of the block have formed therein a respective female socket member, where each female socket member includes a narrow opening which opens into a socket. The socket is for receiving therein an enlarged end of a male tab member of another similarly-constructed block. Each female socket is constructed so that when an enlarged end of a respective male tab member of a neighbor block is received therein, the block and each neighbor block cannot be laterally removed therefrom. The block further includes at least one cable channel formed laterally therethrough. Each cable channel is formed at an acute angle with respect to at least one side of the two sides. 
   In accordance with another embodiment of the invention, disclosed is a erosion control block formed of a heavy material, and having at least four sides, four corners, and a top surface and a bottom surface. Each corner comprises a diagonal face. At least one side of two sides of the block has formed thereon a respective male tab member extending therefrom. The male tab member includes a neck portion and an enlarged end. The block further includes two other sides having formed therein a respective female socket member, where each female socket member includes a narrow opening which opens into a socket. The socket is for receiving therein an enlarged end of a male tab member of another similarly-constructed block. Each female socket is constructed so that when an enlarged end of a respective male tab member of a neighbor block is received therein, the block and each neighbor block cannot be laterally removed therefrom. Also formed in the block is an opening extending from the top surface to the bottom surface thereof. A first cable channel and a second cable channel are formed laterally through the block. The first and second cable channels are formed as conduits in the block so that respective cables can be threaded through the cable channels after the block and neighbor blocks are interlocked together. The first cable channel opens at one thereof at one diagonal corner face and at another end thereof at an opposite diagonal corner face of the block. The second cable channel opening at opposite diagonal corner faces of the block. The first and second cable channels are located in the block so that an axis of the first cable channel forms an “X” with an axis of the second cable channel. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further features and advantages will become apparent from the following and more particular description of the preferred and other embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters generally refer to the same parts, functions or elements throughout the views, and in which: 
       FIG. 1  is a top view of an erosion control block constructed according to the invention; 
       FIG. 2  is a top view of an edge block constructed according to the invention; 
       FIG. 3  is a side view of the erosion control block of  FIG. 1 ; 
       FIG. 4  is a top view of a mat of blocks partially cabled together with six cables; 
       FIG. 5  is a top view of the mat of blocks of  FIG. 4 , but completely cabled together using a full set of twelve cables; 
       FIG. 6  illustrates the blocks of the bottom, left corner of the mat of  FIG. 5 , showing the manner in which the various cables are terminated and secured to hold the blocks together; 
       FIG. 7  is a top view of two mats cabled together; 
       FIG. 8  is a top view of an enlarged portion of a mat of  FIG. 5 , showing the cable pigtail ends extending from the side blocks of the mat; 
       FIGS. 9   a  and  9   b  are respective top views, one an enlarged view, of a portion of adjacent mats, showing in detail the manner in which the pigtail ends are connected together to thereby connect the mats together; and 
       FIG. 10  illustrates another embodiment for connecting together adjacent mats of erosion control blocks. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With reference to  FIGS. 1 and 3 , there is shown respective top and side views of an erosion control block  10  constructed according to one embodiment of the invention. The block  10  includes a body  12  formed with a heavy material, such as concrete. Preferably, although not by necessity, the block  10  can be made by block plant techniques. In forming the erosion control block  10 , the body  12  is formed with four sides, including a north side  14 , an east side  16 , a south side  18  and a west side  20 . The north, east, etc., designations are merely to identify and describe the different attributes of the block  12 , and do not reflect any actual directional or positioning requirements. In terms of size, the block  10  is about fifteen inches between the sides  16  and  20 , and about fifteen inches between the sides  14  and  18 . A block thickness of about 4.5 inches provides a weight of about sixty pounds. In order to achieve a heavier block, it can be made thicker. Formed in the body  12  of the block  10  is an opening  22  extending from the top surface  24  of the block  10  to the bottom surface  26  of the block  10 . The central opening  22  allows vegetation to grow through the block  10  to assist in anchoring the block  10  to the ground. As will be described below, the central opening  22  also provides ready access to the cables extending therethrough. 
   The erosion control block  10  is constructed with each corner formed as a diagonal face. For example, the corner  28  is diagonal to the sides  14  and  20 . The corner  30  is diagonal to the sides  14  and  16 , and the corner  32  is diagonal to the sides  16  and  18 . Lastly, the corner  34  is diagonal to the sides  18  and  20 . In the preferred form of the invention, the corners are made diagonal with an angle of about 45 degrees. As will be described in more detail below, when blocks are arranged in a mat, the diagonal corners of four adjacent blocks form a square opening in the mat. 
   In accordance with an important feature of the invention, cable channels are formed diagonally between opposite corners of the block. For example, a first cable channel  36  is formed through the body  12  of the block  10  from diagonal corner  30  to the opposite diagonal corner  34 . Similarly, a second cable channel  38  is formed between diagonal block corners  28  and  32 . Accordingly, only two cable channels are utilized to provide stability to each block  10  in the mat. The cable channels  36  and  38  are about 0.75 inch in diameter to accommodate at least two cable ropes, each of about 0.25 inch in diameter. As noted in  FIG. 1 , each cable channel  36  and  38  extends through the central opening  22  of the block  10 . This not only facilitates threading of synthetic rope cables through the blocks  10 , but allows attachment of cable pigtail ends thereto in order to tie the edge blocks of one mat to the edge blocks of an adjacent mat. The cable channels  36  and  38  are formed orthogonal to each other, but the intersection of the cable channels  36  and  38  is not in the center of the central opening  22 . This is because the central opening  22  is not in the center of the body  12 , but rather is offset toward the west side  20 . The cable channels  36  and  38  can be formed in the blocks using core puller rods extending horizontally through the block plant form. After the concrete has been poured into the form, the core puller rods can be removed, thereby leaving the cable channels extending through the blocks. It can also be appreciated that the cable channels  36  and  38  are formed at different elevations in the block  10 , as shown in  FIG. 3 . 
   In the preferred embodiment of the invention, the erosion control block  10  is formed with members for interlocking with four adjacent blocks. First and second male tab members  40  and  42  are formed on respective sides  14  and  20 . First and second female socket members  44  and  46  are formed into respective sides  16  and  18 . The male tab member, for example tab member  40 , is formed with a neck portion  48  connecting an enlarged end  50  to the side  14 . The female socket member, such as socket member  44 , is formed with a narrow opening  52  in the side  16 , which opens into a larger socket  54 . The narrow opening  52  of the female socket member  44  accommodates the neck portion  48  of another block (not shown), and the socket  54  accommodates the enlarged end  50  of a tab member of the adjacent block. When the male tab member  40  of one block is inserted into the female socket member  44  of an adjacent block, the two blocks become positively engaged in an interlocking manner and cannot be laterally removed from each other. Four neighboring blocks can be interlocked to the block  10  in the manner described. In other embodiments, the male tab members  40  and  42  can be formed on opposite sides of the body  12  of the block  10 , as can be the female socket members  44  and  46 . 
   The central opening  22  of each block  10  is offset, as noted above. In practice, the central opening  22  is centered between the west side  20  of the body  12  of the block  10 , and the inner sidewall  55  of the female socket member  44 . The central opening  22  is formed centrally between the north side  14  and the south side  18  of the body  12  of the block  10 . 
   All of the erosion control blocks  10  of a mat are of the type shown in  FIG. 1 , with the exception of the blocks on one edge of the mat.  FIG. 2  illustrates an edge block  60  used on one edge of a mat. The edge block  60  is substantially identical to the block  10 , except the edge block  60  is constructed with only one male tab member  40 . The side of the block  60  opposite the female socket member  44  is a planar side  62 , without either a male or female member. The block  60  can be constructed by simply sawing the male tab member  42  off the block  10 . Alternatively, the edge block  60  can be formed by block plant or other means without the male tab member  42 . When an edge of a mat having the edge blocks  60  is placed adjacent another mat of blocks, the absence of the male members on the edge blocks allows easy attachment of the adjacent mats together using cable pigtail ends. This will be described in more detail below. More importantly, the absence of a male tab member extending from the edge of the mat allows easy placement of mats close together, without having to “zipper” the male/female members of the mats together in an interlocking manner. The side of an adjacent mat would have blocks with female socket members. Thus, there is no male/female interlocking relationship between the mats of a system. 
     FIG. 4  illustrates a partially cabled mat  70  of erosion control blocks arranged according to the invention. The mat  70  of the example is an eleven by six matrix of blocks  10 . Mats of many other matrix sizes can be cabled together using the various methods of the invention. A majority of the blocks are the type  10  shown in  FIG. 1 , with the exception of the edge  72 , which includes the edge blocks  60  shown in  FIG. 2 . The cabling of the blocks of the mat  70  includes a plurality of cables, preferably of the synthetic rope type. A first cable  74   1  is shown threaded in a zig-zag manner through one cable channel of eleven blocks of the mat  70 . In the preferred form of the invention, twelve separate cables  74   1 – 74   12  are used to provide a complete zig-zag cabling of the six-by-eleven mat  70  of blocks  10 . 
   The first cable  74   1  is threaded through the blocks in the following manner. The cable  74   1  is first threaded through one cable channel of the top corner block  76 , and then through the cable channels of all the other intermediate blocks to the side block  80 , down to adjacent side block  82 , and then diagonally down through other blocks to the bottom block  84 . The end of the cable  74   1  is left extending from the bottom block  84  until secured in a manner described below. The second cable  74   2  is threaded through the other cable channel of the top corner block  76 , down to adjacent edge block  94 , diagonally down to side block  82 , down to adjacent side block  98 , and then diagonally down to bottom block  104 . Much like the end of cable  74   1  in bottom block  84 , the end of cable  74   2  extends a short distance from the cable channel of the bottom block  104 . The end of each of the twelve cables extends from the respective blocks, and are terminated, as described below. The third cable  74   3  is threaded through the cable channel of top block  92 , diagonally down to side block  88 , down to adjacent side block  80 , and then diagonally down to bottom corner block  86 . The fourth cable  74   4  is threaded through the other cable channel of top block  92 , diagonally down to edge block  94 , down to adjacent edge block  96 , diagonally down to side block  98 , down to adjacent side block  100 , and then diagonally down to bottom block  102 . The fifth cable  74   5  is threaded through the cable channel of top block  90 , diagonally down to side block  89 , down to adjacent side block  88 , diagonally down to edge block  87 , down to adjacent bottom corner block  86 , and then diagonally through the bottom corner block  86 . The sixth cable  74   6  is threaded through the other cable channel of top block  90 , diagonally down to edge block  96 , down to adjacent edge block  117 , diagonally down to side block  100 , down to adjacent side block  120 , and then diagonally down to bottom block  124 . The zig-zag threading pattern of the six cables  74   1 – 74   6  through the blocks of the mat  70  is apparent from  FIG. 4 . 
   The remaining six cables  74   7 – 74   12  are threaded through the blocks of the mat  70 , as shown in  FIG. 5 . The seventh cable  74   7  is threaded through the cable channel of top block  116 , diagonally down to side block  110 , down to adjacent side block  89 , diagonally down to edge block  106 , down to adjacent edge block  87 , and then diagonally down to bottom block  84 . The eight cable  74   8  is threaded through the other cable channel of top block  116 , diagonally down to edge block  117 , down to adjacent edge block  118 , diagonally down to side block  120 , down to adjacent bottom corner block  122 , and then diagonally through the cable channel of the bottom corner block  122 . The ninth cable  74   9  is threaded through the cable channel of top block  114 , diagonally down to side block  112 , down to adjacent side block  110 , diagonally down to edge block  108 , down to adjacent edge block  106 , and then diagonally down to bottom block  104 . The tenth cable  74   10  is threaded through the other cable channel of top block  114 , diagonally down to edge block  118 , down to adjacent edge block  128 , and then diagonally down to and through bottom corner block  122 . The eleventh cable  74   11  is threaded through the cable channel of top corner block  78 , down to adjacent side block  112 , diagonally down to edge block  126 , down to adjacent edge block  108 , and then diagonally down to the bottom block  102 . The twelfth cable  74   12  is threaded through the other cable channel of top corner block  78  and diagonally down to edge block  128 , down to adjacent edge block  126 , and then diagonally down to bottom block  124 . As can be seen from  FIG. 5 , all blocks of the mat  70  are cabled in a zig-zag manner. 
   After the cables  74   1 – 74   12  are threaded through the channels of the blocks in the manner noted, each block is constrained against rotational movement while suspended in the mat  70 . By cabling the blocks diagonally therethrough with two cables, it is expected that fewer blocks will be damaged or broken due to torsional twisting while suspended in the mat  70 . 
   After the cables  74   1 – 74   12  have been threaded through the blocks of the mat  70 , the ends thereof are secured in different ways, depending on the position of the block in the mat  70 . The cables extending from the top and bottom corner blocks are secured to form loops. The other top and bottom blocks are secured together with cable pairs, to also form loops. An example of the manner in which the cable ends of the corner blocks, and top and bottom blocks, are secured is shown in  FIG. 6 . Each corner block is secured in the same way. In threading a corner cable, for example cable  74   10  in  FIG. 6 , the end of the cable is threaded through the top diagonal part  130   a  of the cable channel and into the central opening  134  of the corner block  122 . A sleeve  132  is then slipped over the end of the cable  74   10 , and the remainder of the cable  74   10  is threaded through the bottom diagonal part  130   b  of the cable channel. The end of the cable  74   10  extending from the bottom corner block  122  is made into a loop  136 , and the end of the cable  74   10  threaded back through the bottom diagonal part  130   b  of the cable channel and into the opening  134  of the corner block  122 . In the opening  134 , the end of the cable  74   10  is threaded through the sleeve  132 , and the sleeve  132  is double crimped around both portions of the cable  74   10 . The loop  136  of the cable  74   10  is a point of attachment with the heavy duty hook of a spreader bar. As noted above, the cable ends of the other corner blocks are secured in the same manner. 
   The cable ends of the top and bottom blocks of the mat  70  are secured so as to also provide respective points of attachments for spreader bar hooks. As an example, the cables  74   8  and  74   12  threaded through respective bottom corner block  122  and bottom block  124  are secured in the following manner. During the cable threading procedure, the cable  74   8  is threaded through the top part  131   a  of the cable channel of corner block  122 . A sleeve  133  is then slipped over the cable end, and the remainder of the cable  74   8  is threaded through the lower part  131   b  of the cable channel of bottom corner block  122 . The end of the cable  74   8  is then threaded through the lower part  135   b  of the cable channel of the bottom block  124  and into the opening  139  thereof. 
   The end of the other cable  74   12  is threaded in a similar manner so as to have a sleeve  137  on it in the opening  139  of bottom block  124 , and with the end of cable  74   12  extending into the opening  134  of bottom corner block  122 . The bottom parts  131   b  and  135   b  of the respective cable channels thus have two cables threaded therethrough. The end of cable  74   8  is threaded through the sleeve  133  in the opening  134  of the bottom corner block  122 . The cable  74   8  and the end of cable  74   12  are secured together by double crimping the sleeve  133  thereto. Similarly, the cable  74   12  and the end of cable  74   8  are secured together in the opening of bottom block  124  by double crimping the sleeve  137  thereto. The way the pair of cables  74   8  and  74   12  are secured provides a short loop  141  of two cables at the bottom edge of the mat  70  for attachment by the hook of a spreader bar. The cable pairs of the other top and bottom blocks of the mat  70  are secured in the same manner. The top edge and the bottom edge of the mat  70  are thus provided with multiple points of attachment with the hooks of the spreader bars. When a spreader bar is attached to the top edge of the mat  70 , and another spreader bar is attached to the bottom edge of the mat  70 , via the respective points of attachment, the spreader bars are lifted by a crane. During the process in which the mat  70  is lifted and moved to the location to be installed, the mat  70  bows downwardly. It is at this time that the interlocked blocks of the mat  70  are forced together, thereby subjecting the blocks to pressure against each other, torsional twisting, and possible damage. With the utilization of the invention, block damage is substantially reduced due to the inability of the individual blocks to twist, rotate or turn. 
   As an alternative to the termination of the cable ends described in connection with  FIG. 6 , it is also possible to attach the ends of a pair of cables together in only one opening of a block. For example, those skilled in the art may prefer to thread cable  74   8  through the cable channel  131   a  and terminate the cable end in the opening  134  of corner block  122 . On the other hand, the end of cable  74   12  would be threaded through both cable channels  135   a  and  135   b  of bottom block  124 , and through cable channel  131   b  of corner block  122 , and terminate the end thereof in the opening  134  of corner block  122 . The free ends of the cables  74   8  and  74   12  would be attached together in the opening  134  using one or more double crimped sleeves. 
   Those skilled in the art may find that the starting of the cable threading can be initiated at the sides of the mat, and zig-zag laterally across the mat. For example, the first cable would start at the right, top corner of the mat, and thread the cable diagonally until it reaches the left side of the mat. The remaining cables would be started at the other cable channels at the right side of the mat, and zig-zag across the mat until terminated at the left side of the mat. Some of the cable will only extend diagonally and not zig-zag. While this alternative requires shorter cables, it does require more cables. The cable ends can be secured at the sides of the mat in the manner described above. The use of more cables does, however alleviate the need to thread a long length of one or more cables through many cable channels, which may be more time consuming. 
   As an alternative to the cabling technique described above, those skilled in the art may find that two cables can be used with the mat  70 , which cables would be substantially longer than that described above. In this embodiment, the first cable could be threaded first through a top right corner block, and zig-zag in mat through one cable channel of each block of the mat  70  until the cable exits the top left corner block. The other cable could start at a bottom right corner block and be threaded in a zig-zag manner through the other cable channel of each block of the mat  70  and exit the bottom left corner block. With this cable threading scheme, each cable would be threaded through a cable channel of each block of the mat  70 , irrespective of the length or width of the mat  70 . 
   While various cable threading techniques have been described, those skilled in the art may find yet other threading arrangements to be advantageous. As a further example, one may thread one or more cables through only the first diagonals of the mat (upper right to lower left), and then use one or more other cables for threading through the other diagonals (upper left to lower right). In this case, no cable itself is threaded in a zig-zag manner. The various cable threading arrangements can accommodate many different mat widths and lengths, and thus numbers of blocks in a mat. Thus, if different size mats are required for different area requirements, then it is an easy task to determine the number of blocks required to cover the area, the number of columns and rows in the mat, and then cable the mats according to the threading techniques of the invention. Many other arrangements are possible, including variations and combinations of the cable threading techniques described herein. 
     FIG. 7  illustrates two mats  70  and  143  of erosion control blocks individually cabled together according to the technique described above in connection with  FIG. 5 . The mats  70  and  143  are lowered to the location to be protected against erosion, and laid adjacent each other, as shown. In order to provide a system of mats tied together, the side edges of the adjacent mats are secured together with short cables and tied together to provide an overall integrity throughout the system of mats. While only two mats  70  and  132  are shown in  FIG. 7 , many other mats can be attached together in the same manner to provide a large area of ground coverage and prevent erosion thereof. Since the cables  74   1 – 74   12  used to cable a mat together are routed between adjacent blocks at the side edges of the mat  70 , no free cable ends are available that can be used to tie or otherwise attach the mats together. Accordingly, pigtail cable ends are provided at a plurality of locations between adjacent mats to attach the mats together after they have been placed together at the desired location. 
     FIG. 8  illustrates a configuration  140  of erosion control blocks of a mat, where the side blocks  142  and  144  are provided with respective pigtail cable ends  146  and  148 . The other side blocks and edge blocks of the mat can be provided with pigtail cable ends in a similar manner. The side block  145  is cabled to adjacent side block  142  by cable  152 , in the manner described above. The cable  152  effectively zigs through side block  145 , is looped, and then zags through side block  142  to form a zig-zag pattern. In like manner, the cable  150  is threaded through both side blocks  142  and  144 . Cable  147  is threaded through adjacent side blocks  144  and  151 . In order to provide free cable ends, a short length of cable is attached to each of the cables  147 ,  150  and  152  at the location of each side block. For example, a cable pigtail  146  of about eighteen inches long is attached to the cable  150 . The end of the cable pigtail  146  is looped around the cable  150 , and fastened to itself by a sleeve  154 . The sleeve  154  is aluminum, is commercially available, and made for crimping synthetic rope-type cables together. In practice, the sleeve  154  is double crimped for purposes of reliability. The cable channel  156  formed in block  142  is of sufficient diameter to accommodate two cables threaded therethrough. Importantly, the connection between the cable pigtail  146  and cable  150  is made inside the opening  158  of the side block  142 . The opening  158  formed in the block  146  provides excellent accessibility to, and room for crimping a connection for achoring the two cables together. The free end of the cable pigtail  146  is available for attachment to an adjacent mat of blocks. 
   Another cable pigtail  148  is provided by threading a short piece of cable through the cable channel  160  of side block  144 . The end of the cable pigtail  148  is looped around the cable  147  and fastened to itself by a crimped sleeve  164 . The connection between the cable pigtail  148  and the cable  147  is made in the opening  162  of the side block  144 . The free end of the cable pigtail  148  is available for attachment to the adjacent mat of blocks. Cable pigtails can be attached to the other cables exposed at the edge blocks and the side blocks of the mat in a similar manner. Accordingly, each side of the mat is provided with free cable ends for connection to adjacent mats. 
     FIG. 9   a  illustrates the manner in which the adjacent mats are connected together using the cable pigtails. The block arrangement  140  is associated with a first mat, and the block arrangement  170  is associated with a second, adjacent mat. The block arrangement  170  includes edge blocks  172  and  174 , with respective openings  176  and  178  formed therein. A cable pigtail  180  is crimped by a sleeve  182  around cable  183 . Similarly, a cable pigtail  184  is crimped by a sleeve  186  around cable  187  in the opening  178  of edge block  174 . 
     FIG. 9   b  is an enlarged view illustrating the manner in which the cable pigtail of one mat is attached to the cable pigtail of an adjacent mat. At the corner formed by side blocks  142  and  144 , and edge blocks  172  and  174 , there is formed a square opening  190 . The free ends of the cable pigtails  148  and  184  are available in the opening  190 . A sleeve  192  is placed around the free ends of the cable pigtails  148  and  184  and double crimped thereto. Each of the cable pigtails of the side blocks of the configuration  140  are attached to the cable pigtails of the block configuration  170  in a similar manner. The respective cables  150  of the one mat and the cable  183  of the adjacent mat are thus attached together and separation of the mats is prevented. 
   While each side and edge block of the preferred embodiment are pigtailed, those skilled in the art may find that in some applications, not every side and corresponding edge block need be pigtailed. Rather, the pigtailing of every other side and edge block may be sufficient. As an alternative to the use of cable pigtails, the cables of each mat can be connected together by using a short cable  212 , as shown in  FIG. 10 . Here, the cable  204  is threaded between side blocks  200  and  202  of a mat in the same manner as described above in connection with  FIG. 5 . An adjacent mat has edge blocks  206  and  208  held together with a cable  210 . In order to attach the side blocks of one mat to the edge blocks of an adjacent mat, a single short length of cable  212  is wrapped around that portion of the cables  204  and  210  exposed in the square opening  216 . The ends of the short cable  212  are attached together by crimping one or two sleeves  214  thereto. Depending on the situation, the short cable  212  can be wrapped around the exposed cables  204  and  210  of adjacent mats twice. The exposed portions of the other cables of the adjacent mats can be attached together in a similar manner. 
   The foregoing description contemplates that the mats of erosion control blocks are made with a sufficient number of blocks in length such that the mats only need to be attached at the sides and edges in order to make a system of mats. This arrangement functions adequately when the ground area to be covered is much longer in one dimension than the other. When large areas, both as to length and width, are required to be covered with the mats of erosion control blocks according to the invention, then the mats need to be attached to each other not only at the sides, but also at the top and bottom edges. Mats of erosion control blocks cannot generally be made with extremely long widths or lengths because of weight considerations, as well as the size of the cables required to carry the corresponding load. To that end, the top and bottom ends of the mats can be attached together with cable pigtail ends, much like that described above in conjunction with  FIGS. 8 and 9 . In this situation, the cable channels of the blocks would have to accommodate three cables. Nevertheless, the mats can be attached together in a large two dimensional erosion prevention system to cover a large surface area of the ground. 
   In the contemplated applications, it is expected that the mats of erosion control blocks would be lifted and moved using a crane and a spreader bar. However, the erosion control blocks can be hand laid at the location, and ropes threaded through the blocks in the same zig-zag manner described above. The mats can also be attached together at the sides thereof using the techniques set forth above. 
   From the foregoing, disclosed is an erosion control block and a method of cabling the same together to provide a mat of blocks, where each block of the mat is suspended by a pair of cables which exit the blocks at the corners thereof. Disclosed also is a technique for cabling together adjacent mats of erosion control blocks to provide a large area of coverage and prevent erosion of the underlying ground. While the invention is described in connection with a preferred embodiment using interlocking blocks, the utilization of the invention does not require that the blocks be of the interlocking type. Rather, block design that are not interlocking at all, such as the type described in U.S. Pat. No. 4,375,928 by Crow et al., and blocks that are only interengaging, such as disclosed in U.S. Pat. No. 5,020,938 by Scales and U.S. Pat. No. 6,484,230 by Rudloff, can be utilized with the principles and concepts of the invention. 
   While the preferred and other embodiments of the invention have been disclosed with reference to specific blocks and cabling techniques, it is to be understood that many changes in detail may be made as a matter of engineering choices without departing from the spirit and scope of the invention, as defined by the appended claims.